Avoid reading from Viper for path and URL funcs

The gain, given the "real sites benchmark" below, is obvious:

```
benchmark           old ns/op       new ns/op       delta
BenchmarkHugo-4     14497594101     13084156335     -9.75%

benchmark           old allocs     new allocs     delta
BenchmarkHugo-4     57404335       48282002       -15.89%

benchmark           old bytes       new bytes      delta
BenchmarkHugo-4     9933505624      9721984424     -2.13%
```

Fixes #2495

12 files changed, 85 insertions, 48 deletions

diff --git a/hugolib/hugo_sites_test.go b/hugolib/hugo_sites_test.go
index b7a52b1e4..be2ba9803 100644
--- a/hugolib/hugo_sites_test.go
+++ b/hugolib/hugo_sites_test.go
@@ -35,6 +35,7 @@ func testCommonResetState() {
 	hugofs.InitMemFs()
 	viper.Reset()
 	viper.SetFs(hugofs.Source())
+	helpers.ResetConfigProvider()
 	loadDefaultSettings()
 
 	// Default is false, but true is easier to use as default in tests
diff --git a/hugolib/node.go b/hugolib/node.go
index eefb78bec..16c83e2e8 100644
--- a/hugolib/node.go
+++ b/hugolib/node.go
@@ -178,7 +178,7 @@ func (n *Node) URL() string {
 }
 
 func (n *Node) Permalink() string {
-	return permalink(n.URL())
+	return n.Site.permalink(n.URL())
 }
 
 // Scratch returns the writable context associated with this Node.
diff --git a/hugolib/page.go b/hugolib/page.go
index fee7c334a..484425697 100644
--- a/hugolib/page.go
+++ b/hugolib/page.go
@@ -569,9 +569,9 @@ func (p *Page) analyzePage() {
 
 func (p *Page) permalink() (*url.URL, error) {
 	baseURL := string(p.Site.BaseURL)
-	dir := strings.TrimSpace(helpers.MakePath(filepath.ToSlash(strings.ToLower(p.Source.Dir()))))
-	pSlug := strings.TrimSpace(helpers.URLize(p.Slug))
-	pURL := strings.TrimSpace(helpers.URLize(p.URLPath.URL))
+	dir := strings.TrimSpace(p.Site.pathSpec.MakePath(filepath.ToSlash(strings.ToLower(p.Source.Dir()))))
+	pSlug := strings.TrimSpace(p.Site.pathSpec.URLize(p.Slug))
+	pURL := strings.TrimSpace(p.Site.pathSpec.URLize(p.URLPath.URL))
 	var permalink string
 	var err error
 
@@ -1171,5 +1171,6 @@ func (p *Page) TargetPath() (outfile string) {
 		outfile = helpers.ReplaceExtension(p.Source.TranslationBaseName(), p.Extension())
 	}
 
-	return p.addLangFilepathPrefix(filepath.Join(strings.ToLower(helpers.MakePath(p.Source.Dir())), strings.TrimSpace(outfile)))
+	return p.addLangFilepathPrefix(filepath.Join(strings.ToLower(
+		p.Site.pathSpec.MakePath(p.Source.Dir())), strings.TrimSpace(outfile)))
 }
diff --git a/hugolib/pageSort_test.go b/hugolib/pageSort_test.go
index 23a3fd07c..738fcc80e 100644
--- a/hugolib/pageSort_test.go
+++ b/hugolib/pageSort_test.go
@@ -20,6 +20,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/spf13/hugo/helpers"
 	"github.com/spf13/hugo/source"
 	"github.com/stretchr/testify/assert"
 )
@@ -134,6 +135,8 @@ func setSortVals(dates [3]time.Time, titles [3]string, weights [3]int, pages Pag
 func createSortTestPages(num int) Pages {
 	pages := make(Pages, num)
 
+	info := newSiteInfo(siteBuilderCfg{baseURL: "http://base", language: helpers.NewDefaultLanguage()})
+
 	for i := 0; i < num; i++ {
 		pages[i] = &Page{
 			Node: Node{
@@ -141,7 +144,7 @@ func createSortTestPages(num int) Pages {
 					Section: "z",
 					URL:     fmt.Sprintf("http://base/x/y/p%d.html", i),
 				},
-				Site: newSiteInfoDefaultLanguage("http://base/"),
+				Site: &info,
 			},
 			Source: Source{File: *source.NewFile(filepath.FromSlash(fmt.Sprintf("/x/y/p%d.md", i)))},
 		}
diff --git a/hugolib/page_permalink_test.go b/hugolib/page_permalink_test.go
index d185bebab..eb3a6c878 100644
--- a/hugolib/page_permalink_test.go
+++ b/hugolib/page_permalink_test.go
@@ -18,6 +18,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/spf13/hugo/helpers"
 	"github.com/spf13/hugo/source"
 	"github.com/spf13/viper"
 )
@@ -59,17 +60,18 @@ func TestPermalink(t *testing.T) {
 	}
 
 	viper.Set("DefaultExtension", "html")
-
 	for i, test := range tests {
 		viper.Set("uglyurls", test.uglyURLs)
 		viper.Set("canonifyurls", test.canonifyURLs)
+		info := newSiteInfo(siteBuilderCfg{baseURL: string(test.base), language: helpers.NewDefaultLanguage()})
+
 		p := &Page{
 			Node: Node{
 				URLPath: URLPath{
 					Section: "z",
 					URL:     test.url,
 				},
-				Site: newSiteInfoDefaultLanguage(string(test.base)),
+				Site: &info,
 			},
 			Source: Source{File: *source.NewFile(filepath.FromSlash(test.file))},
 		}
diff --git a/hugolib/page_test.go b/hugolib/page_test.go
index 0bb924f01..342ff3bd5 100644
--- a/hugolib/page_test.go
+++ b/hugolib/page_test.go
@@ -1122,7 +1122,8 @@ func TestPagePaths(t *testing.T) {
 
 	for _, test := range tests {
 		p, _ := NewPageFrom(strings.NewReader(test.content), filepath.FromSlash(test.path))
-		p.Node.Site = newSiteInfoDefaultLanguage("")
+		info := newSiteInfo(siteBuilderCfg{language: helpers.NewDefaultLanguage()})
+		p.Node.Site = &info
 
 		if test.hasPermalink {
 			p.Node.Site.Permalinks = siteParmalinksSetting
diff --git a/hugolib/pagination.go b/hugolib/pagination.go
index 5bba5d89f..81f3e0cda 100644
--- a/hugolib/pagination.go
+++ b/hugolib/pagination.go
@@ -508,16 +508,16 @@ func newPaginator(elements []paginatedElement, total, size int, urlFactory pagin
 }
 
 func newPaginationURLFactory(pathElements ...string) paginationURLFactory {
-	paginatePath := helpers.Config().GetString("paginatePath")
+	pathSpec := helpers.CurrentPathSpec()
 
 	return func(page int) string {
 		var rel string
 		if page == 1 {
 			rel = fmt.Sprintf("/%s/", path.Join(pathElements...))
 		} else {
-			rel = fmt.Sprintf("/%s/%s/%d/", path.Join(pathElements...), paginatePath, page)
+			rel = fmt.Sprintf("/%s/%s/%d/", path.Join(pathElements...), pathSpec.PaginatePath(), page)
 		}
 
-		return helpers.URLizeAndPrep(rel)
+		return pathSpec.URLizeAndPrep(rel)
 	}
 }
diff --git a/hugolib/pagination_test.go b/hugolib/pagination_test.go
index 786650469..7bbc38058 100644
--- a/hugolib/pagination_test.go
+++ b/hugolib/pagination_test.go
@@ -19,6 +19,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/spf13/hugo/helpers"
 	"github.com/spf13/hugo/source"
 	"github.com/spf13/viper"
 	"github.com/stretchr/testify/assert"
@@ -453,6 +454,7 @@ func TestPage(t *testing.T) {
 func createTestPages(num int) Pages {
 	pages := make(Pages, num)
 
+	info := newSiteInfo(siteBuilderCfg{baseURL: "http://base/", language: helpers.NewDefaultLanguage()})
 	for i := 0; i < num; i++ {
 		pages[i] = &Page{
 			Node: Node{
@@ -460,7 +462,7 @@ func createTestPages(num int) Pages {
 					Section: "z",
 					URL:     fmt.Sprintf("http://base/x/y/p%d.html", i),
 				},
-				Site: newSiteInfoDefaultLanguage("http://base/"),
+				Site: &info,
 			},
 			Source: Source{File: *source.NewFile(filepath.FromSlash(fmt.Sprintf("/x/y/p%d.md", i)))},
 		}
diff --git a/hugolib/permalinks.go b/hugolib/permalinks.go
index 581f8740f..c149ae13d 100644
--- a/hugolib/permalinks.go
+++ b/hugolib/permalinks.go
@@ -19,8 +19,6 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
-
-	"github.com/spf13/hugo/helpers"
 )
 
 // pathPattern represents a string which builds up a URL from attributes
@@ -152,14 +150,14 @@ func pageToPermalinkDate(p *Page, dateField string) (string, error) {
 func pageToPermalinkTitle(p *Page, _ string) (string, error) {
 	// Page contains Node which has Title
 	// (also contains URLPath which has Slug, sometimes)
-	return helpers.URLize(p.Title), nil
+	return p.Site.pathSpec.URLize(p.Title), nil
 }
 
 // pageToPermalinkFilename returns the URL-safe form of the filename
 func pageToPermalinkFilename(p *Page, _ string) (string, error) {
 	//var extension = p.Source.Ext
 	//var name = p.Source.Path()[0 : len(p.Source.Path())-len(extension)]
-	return helpers.URLize(p.Source.TranslationBaseName()), nil
+	return p.Site.pathSpec.URLize(p.Source.TranslationBaseName()), nil
 }
 
 // if the page has a slug, return the slug, else return the title
@@ -173,7 +171,7 @@ func pageToPermalinkSlugElseTitle(p *Page, a string) (string, error) {
 		if strings.HasSuffix(p.Slug, "-") {
 			p.Slug = p.Slug[0 : len(p.Slug)-1]
 		}
-		return helpers.URLize(p.Slug), nil
+		return p.Site.pathSpec.URLize(p.Slug), nil
 	}
 	return pageToPermalinkTitle(p, a)
 }
diff --git a/hugolib/permalinks_test.go b/hugolib/permalinks_test.go
index 672cf2d66..bdc96d41a 100644
--- a/hugolib/permalinks_test.go
+++ b/hugolib/permalinks_test.go
@@ -16,6 +16,8 @@ package hugolib
 import (
 	"strings"
 	"testing"
+
+	"github.com/spf13/hugo/helpers"
 )
 
 // testdataPermalinks is used by a couple of tests; the expandsTo content is
@@ -70,6 +72,8 @@ func TestPermalinkValidation(t *testing.T) {
 
 func TestPermalinkExpansion(t *testing.T) {
 	page, err := NewPageFrom(strings.NewReader(simplePageJSON), "blue/test-page.md")
+	info := newSiteInfo(siteBuilderCfg{language: helpers.NewDefaultLanguage()})
+	page.Site = &info
 	if err != nil {
 		t.Fatalf("failed before we began, could not parse SIMPLE_PAGE_JSON: %s", err)
 	}
diff --git a/hugolib/site.go b/hugolib/site.go
index f6a787298..7f96bb5aa 100644
--- a/hugolib/site.go
+++ b/hugolib/site.go
@@ -117,7 +117,8 @@ func (s *Site) reset() *Site {
 
 // newSite creates a new site in the given language.
 func newSite(lang *helpers.Language) *Site {
-	return &Site{Language: lang, Info: SiteInfo{multilingual: newMultiLingualForLanguage(lang)}}
+	return &Site{Language: lang, Info: newSiteInfo(siteBuilderCfg{language: lang})}
+
 }
 
 // newSite creates a new site in the default language.
@@ -139,9 +140,12 @@ func newSiteFromSources(pathContentPairs ...string) *Site {
 		sources = append(sources, source.ByteSource{Name: filepath.FromSlash(path), Content: []byte(content)})
 	}
 
+	lang := helpers.NewDefaultLanguage()
+
 	return &Site{
 		Source:   &source.InMemorySource{ByteSource: sources},
-		Language: helpers.NewDefaultLanguage(),
+		Language: lang,
+		Info:     newSiteInfo(siteBuilderCfg{language: lang}),
 	}
 }
 
@@ -195,16 +199,25 @@ type SiteInfo struct {
 	LanguagePrefix                 string
 	Languages                      helpers.Languages
 	defaultContentLanguageInSubdir bool
+
+	pathSpec *helpers.PathSpec
 }
 
 // Used in tests.
-func newSiteInfoDefaultLanguage(baseURL string, pages ...*Page) *SiteInfo {
-	ps := Pages(pages)
 
-	return &SiteInfo{
-		BaseURL:      template.URL(baseURL),
-		rawAllPages:  &ps,
-		multilingual: newMultiLingualDefaultLanguage(),
+type siteBuilderCfg struct {
+	language *helpers.Language
+	baseURL  string
+
+	pages *Pages
+}
+
+func newSiteInfo(cfg siteBuilderCfg) SiteInfo {
+	return SiteInfo{
+		BaseURL:      template.URL(cfg.baseURL),
+		rawAllPages:  cfg.pages,
+		pathSpec:     helpers.NewPathSpecFromConfig(cfg.language),
+		multilingual: newMultiLingualForLanguage(cfg.language),
 	}
 }
 
@@ -808,7 +821,9 @@ func (s *Site) setCurrentLanguageConfig() error {
 	// There are sadly some global template funcs etc. that need the language information.
 	viper.Set("Multilingual", s.multilingualEnabled())
 	viper.Set("CurrentContentLanguage", s.Language)
-	return tpl.SetTranslateLang(s.Language.Lang)
+	// Cache the current config.
+	helpers.InitConfigProviderForCurrentContentLanguage()
+	return tpl.SetTranslateLang(s.Language)
 }
 
 func (s *Site) render() (err error) {
@@ -887,7 +902,7 @@ func (s *SiteInfo) HomeAbsURL() string {
 	if s.IsMultiLingual() {
 		base = s.Language.Lang
 	}
-	return helpers.AbsURL(base, false)
+	return s.pathSpec.AbsURL(base, false)
 }
 
 // SitemapAbsURL is a convenience method giving the absolute URL to the sitemap.
@@ -946,7 +961,6 @@ func (s *Site) initializeSiteInfo() {
 		Languages:                      languages,
 		defaultContentLanguageInSubdir: defaultContentInSubDir,
 		GoogleAnalytics:                lang.GetString("GoogleAnalytics"),
-		RSSLink:                        permalinkStr(lang.GetString("RSSUri")),
 		BuildDrafts:                    viper.GetBool("BuildDrafts"),
 		canonifyURLs:                   viper.GetBool("CanonifyURLs"),
 		preserveTaxonomyNames:          lang.GetBool("PreserveTaxonomyNames"),
@@ -959,7 +973,10 @@ func (s *Site) initializeSiteInfo() {
 		Permalinks:                     permalinks,
 		Data:                           &s.Data,
 		owner:                          s.owner,
+		pathSpec:                       helpers.NewPathSpecFromConfig(lang),
 	}
+
+	s.Info.RSSLink = s.Info.permalinkStr(lang.GetString("RSSUri"))
 }
 
 func (s *Site) hasTheme() bool {
@@ -1407,7 +1424,7 @@ func (s *SiteInfo) createNodeMenuEntryURL(in string) string {
 	}
 	// make it match the nodes
 	menuEntryURL := in
-	menuEntryURL = helpers.SanitizeURLKeepTrailingSlash(helpers.URLize(menuEntryURL))
+	menuEntryURL = helpers.SanitizeURLKeepTrailingSlash(s.pathSpec.URLize(menuEntryURL))
 	if !s.canonifyURLs {
 		menuEntryURL = helpers.AddContextRoot(string(s.BaseURL), menuEntryURL)
 	}
@@ -1586,13 +1603,13 @@ func (s *Site) renderAliases() error {
 	if s.owner.multilingual.enabled() {
 		mainLang := s.owner.multilingual.DefaultLang.Lang
 		if s.Info.defaultContentLanguageInSubdir {
-			mainLangURL := helpers.AbsURL(mainLang, false)
+			mainLangURL := s.Info.pathSpec.AbsURL(mainLang, false)
 			jww.DEBUG.Printf("Write redirect to main language %s: %s", mainLang, mainLangURL)
 			if err := s.publishDestAlias(s.languageAliasTarget(), "/", mainLangURL, nil); err != nil {
 				return err
 			}
 		} else {
-			mainLangURL := helpers.AbsURL("", false)
+			mainLangURL := s.Info.pathSpec.AbsURL("", false)
 			jww.DEBUG.Printf("Write redirect to main language %s: %s", mainLang, mainLangURL)
 			if err := s.publishDestAlias(s.languageAliasTarget(), mainLang, mainLangURL, nil); err != nil {
 				return err
@@ -1763,7 +1780,7 @@ func (s *Site) newTaxonomyNode(prepare bool, t taxRenderInfo, counter int) (*Nod
 	n := s.nodeLookup(fmt.Sprintf("tax-%s-%s", t.plural, key), counter, prepare)
 
 	if s.Info.preserveTaxonomyNames {
-		key = helpers.MakePathSanitized(key)
+		key = s.Info.pathSpec.MakePathSanitized(key)
 	}
 	base := t.plural + "/" + key
 
@@ -1952,7 +1969,7 @@ func (s *Site) renderSectionLists(prepare bool) error {
 			[]string{"section/" + section + ".html", "_default/section.html", "_default/list.html", "indexes/" + section + ".html", "_default/indexes.html"})
 
 		if s.Info.preserveTaxonomyNames {
-			section = helpers.MakePathSanitized(section)
+			section = s.Info.pathSpec.MakePathSanitized(section)
 		}
 
 		base := n.addLangPathPrefix(section)
@@ -1966,7 +1983,7 @@ func (s *Site) renderSectionLists(prepare bool) error {
 			paginatePath := helpers.Config().GetString("paginatePath")
 
 			// write alias for page 1
-			s.writeDestAlias(helpers.PaginateAliasPath(base, 1), permalink(base), nil)
+			s.writeDestAlias(helpers.PaginateAliasPath(base, 1), s.Info.permalink(base), nil)
 
 			pagers := n.paginator.Pagers()
 
@@ -2111,6 +2128,15 @@ func (s *Site) newHomeNode(prepare bool, counter int) *Node {
 	return n
 }
 
+func (s *Site) newPage() *Page {
+	page := &Page{}
+	page.language = s.Language
+	page.Date = s.Info.LastChange
+	page.Lastmod = s.Info.LastChange
+	page.Site = &s.Info
+	return page
+}
+
 func (s *Site) renderSitemap() error {
 	if viper.GetBool("DisableSitemap") {
 		return nil
@@ -2123,11 +2149,7 @@ func (s *Site) renderSitemap() error {
 	// Prepend homepage to the list of pages
 	pages := make(Pages, 0)
 
-	page := &Page{}
-	page.language = s.Language
-	page.Date = s.Info.LastChange
-	page.Lastmod = s.Info.LastChange
-	page.Site = &s.Info
+	page := s.newPage()
 	page.URLPath.URL = ""
 	page.Sitemap.ChangeFreq = sitemapDefault.ChangeFreq
 	page.Sitemap.Priority = sitemapDefault.Priority
@@ -2199,18 +2221,21 @@ func (s *Site) Stats() {
 }
 
 func (s *Site) setURLs(n *Node, in string) {
-	n.URLPath.URL = helpers.URLizeAndPrep(in)
-	n.URLPath.Permalink = permalink(n.URLPath.URL)
-	n.RSSLink = template.HTML(permalink(in + ".xml"))
+	n.URLPath.URL = s.Info.pathSpec.URLizeAndPrep(in)
+	n.URLPath.Permalink = s.Info.permalink(n.URLPath.URL)
+	n.RSSLink = template.HTML(s.Info.permalink(in + ".xml"))
 }
 
-func permalink(plink string) string {
-	return permalinkStr(plink)
+func (s *SiteInfo) permalink(plink string) string {
+	return s.permalinkStr(plink)
 }
 
-func permalinkStr(plink string) string {
-	return helpers.MakePermalink(viper.GetString("BaseURL"), helpers.URLizeAndPrep(plink)).String()
+func (s *SiteInfo) permalinkStr(plink string) string {
+	return helpers.MakePermalink(
+		viper.GetString("BaseURL"),
+		s.pathSpec.URLizeAndPrep(plink)).String()
 }
+
 func (s *Site) newNode(nodeID string) *Node {
 	return s.nodeLookup(nodeID, 0, true)
 }
diff --git a/hugolib/taxonomy.go b/hugolib/taxonomy.go
index ffe586ffc..112d22b37 100644
--- a/hugolib/taxonomy.go
+++ b/hugolib/taxonomy.go
@@ -52,7 +52,7 @@ type OrderedTaxonomyEntry struct {
 
 // KeyPrep... Taxonomies should be case insensitive. Can make it easily conditional later.
 func kp(in string) string {
-	return helpers.MakePathSanitized(in)
+	return helpers.CurrentPathSpec().MakePathSanitized(in)
 }
 
 // Get the weighted pages for the given key.