diff --git a/DomainParser/DomainParser/BasicRulesParser.swift b/DomainParser/DomainParser/BasicRulesParser.swift
index 44cc60f..e5bd2dc 100644
--- a/DomainParser/DomainParser/BasicRulesParser.swift
+++ b/DomainParser/DomainParser/BasicRulesParser.swift
@@ -16,7 +16,7 @@ public struct BasicRulesParser {
     }
     public func parse(host: String) -> ParsedHost? {
         let lowercasedHost = host.lowercased()
-        let hostComponents = lowercasedHost.components(separatedBy: ".")
+        let hostComponents = lowercasedHost.split(separator: ".")
         var hostSlices = ArraySlice(hostComponents)
         
         /// A host must have at least two parts else it's a TLD
diff --git a/DomainParser/DomainParser/DomainParser.swift b/DomainParser/DomainParser/DomainParser.swift
index 89f2c39..e90e779 100644
--- a/DomainParser/DomainParser/DomainParser.swift
+++ b/DomainParser/DomainParser/DomainParser.swift
@@ -41,7 +41,7 @@ public struct DomainParser {
      }
     
     func parseExceptionsAndWildCardRules(host: String) -> ParsedHost? {
-        let hostComponents = host.components(separatedBy: ".")
+        let hostComponents = host.split(separator: ".")
         let isMatching: (Rule) -> Bool =  { $0.isMatching(hostLabels: hostComponents) }
         let rule = parsedRules.exceptions.first(where: isMatching) ?? parsedRules.wildcardRules.first(where: isMatching)
         return rule?.parse(hostLabels: hostComponents)
diff --git a/DomainParser/DomainParser/Model/Rule.swift b/DomainParser/DomainParser/Model/Rule.swift
index 4718601..e638a32 100644
--- a/DomainParser/DomainParser/Model/Rule.swift
+++ b/DomainParser/DomainParser/Model/Rule.swift
@@ -23,12 +23,12 @@ struct Rule {
     /// Score used to sort the rules. If a URL match multiple rules, the one with the highest Score is prevailing
     let rankingScore: Int
 
-    init(raw: String) {
+    init(raw: Substring) {
 
         /// If the line starts with "!" it's an exceptional Rule
         exception = raw.starts(with: C.exceptionMarker)
-        source = exception ? String(raw.dropFirst()) : raw
-        parts = source.components(separatedBy: ".").map(RuleLabel.init)
+        source = exception ? String(raw.dropFirst()) : String(raw)
+        parts = source.split(separator: ".").map(RuleLabel.init)
 
         /// Exceptions should have a higher Rank than regular rules
         rankingScore = (exception ? 1000 : 0) + parts.count
@@ -44,7 +44,7 @@ extension Rule {
     /// - Beginning with the right-most labels of both the domain and the rule,
     ///     and continuing for all labels in the rule, one finds that for every pair,
     ///     either they are identical, or that the label from the rule is "*".
-    func isMatching(hostLabels: [String]) -> Bool {
+    func isMatching(hostLabels: [Substring]) -> Bool {
         let delta = hostLabels.count - self.parts.count
 
         /// The url should have at least the same number of labels than the url
@@ -55,7 +55,7 @@ extension Rule {
 
         let zipped = zip(self.parts, trimmedHostLabels)
         /// Closure that check if a RuleLabel match a given string
-        let matchingClosure:(RuleLabel, String) -> Bool = {ruleComponent, hostComponent in
+        let matchingClosure:(RuleLabel, Substring) -> Bool = {ruleComponent, hostComponent in
             return ruleComponent.isMatching(label: hostComponent)
         }
         
@@ -73,7 +73,7 @@ extension Rule {
         
 
     /// ⚠️ Should be called only for host matching the rule
-    func parse(hostLabels: [String]) -> ParsedHost {
+    func parse(hostLabels: [Substring]) -> ParsedHost {
         let partsCount =  parts.count - (self.exception ? 1 : 0)
         let delta = hostLabels.count - partsCount
 
diff --git a/DomainParser/DomainParser/Model/RuleLabel.swift b/DomainParser/DomainParser/Model/RuleLabel.swift
index 5488c71..f764b5c 100644
--- a/DomainParser/DomainParser/Model/RuleLabel.swift
+++ b/DomainParser/DomainParser/Model/RuleLabel.swift
@@ -14,12 +14,12 @@ enum RuleLabel {
     /// Wildcards are not restricted to appear only in the leftmost position, but they must wildcard an entire label. (I.e. *.*.foo is a valid rule: *bar.foo is not.)
     case wildcard
 
-    init(fromComponent component: String) {
-        self = component == Constant.wildcardComponent ? .wildcard : .text(component)
+    init(fromComponent component: Substring) {
+        self = component == Constant.wildcardComponent ? .wildcard : .text(String(component))
     }
 
     /// Return true if self matches the given label
-    func isMatching(label: String) -> Bool {
+    func isMatching(label: Substring) -> Bool {
         switch self {
         case let .text(text):
             return text == label
diff --git a/DomainParser/DomainParser/RulesParser.swift b/DomainParser/DomainParser/RulesParser.swift
index a2a7682..ade2441 100644
--- a/DomainParser/DomainParser/RulesParser.swift
+++ b/DomainParser/DomainParser/RulesParser.swift
@@ -22,24 +22,20 @@ class RulesParser {
             throw DomainParserError.parsingError(details: nil)
         }
         rulesText
-            .components(separatedBy: .newlines)
+            .split(separator: "\n")
             .forEach(parseRule)
         return ParsedRules.init(exceptions: exceptions,
                                 wildcardRules: wildcardRules,
                                 basicRules: basicRules)
     }
-    
-    private func parseRule(line: String) {
-        guard let trimmedLine = line.components(separatedBy: .whitespaces).first,
-            !trimmedLine.isComment && !trimmedLine.isEmpty else { return }
-        
-        /// From `publicsuffix.org/list/` Each line is only read up to the first whitespace; entire lines can also be commented using //.
-        if trimmedLine.contains("*") {
-            wildcardRules.append(Rule(raw: trimmedLine))
-        } else if trimmedLine.starts(with: "!") {
-            exceptions.append(Rule(raw: trimmedLine))
+
+    private func parseRule(line: Substring) {
+        if line.contains("*") {
+            wildcardRules.append(Rule(raw: line))
+        } else if line.starts(with: "!") {
+            exceptions.append(Rule(raw: line))
         } else {
-            basicRules.insert(trimmedLine)
+            basicRules.insert(String(line))
         }
     }
 }
diff --git a/script/UpdatePSL.swift b/script/UpdatePSL.swift
index 92ed464..b850a04 100644
--- a/script/UpdatePSL.swift
+++ b/script/UpdatePSL.swift
@@ -44,7 +44,8 @@ struct PublicSuffixListMinimifier {
     init(data: Data) {
         self.data = data
     }
-    // A valid line is a non-empty, non-comment line
+
+    /// A valid line is a non-empty, non-comment line
     func isLineValid(line: String) -> Bool {
         return !line.isEmpty && !line.starts(with: "//")
     }
@@ -52,6 +53,7 @@ struct PublicSuffixListMinimifier {
     func minimify() throws -> Data {
         guard let stringifiedData = String.init(data: data, encoding: .utf8) else { throw ErrorType.notUTF8Convertible(data: data) }
 
+        //  From `publicsuffix.org/list/` Each line is only read up to the first whitespace; entire lines can also be commented using //.
         let validLinesArray = stringifiedData.components(separatedBy: .newlines)
             .map { $0.trimmingCharacters(in: CharacterSet.whitespaces) }
             .compactMap { $0.components(separatedBy: CharacterSet.whitespaces).first }