diff --git a/lib/pages/games.rb b/lib/pages/games.rb
index e4fe3de..8da77f0 100644
--- a/lib/pages/games.rb
+++ b/lib/pages/games.rb
@@ -47,7 +47,7 @@ module W3DHubLauncher
       def blur
         @parent.hide_battleview_panel
 
-        CyberarmEngine::EventBus.unsubscribe("application_changed")
+        CyberarmEngine::EventBus.unsubscribe("application_changed", self)
       end
 
       def populate_game_content_container
diff --git a/lib/worker/api/legacy_manifest_package.rb b/lib/worker/api/legacy_manifest_package.rb
index 88bf519..9b2054b 100644
--- a/lib/worker/api/legacy_manifest_package.rb
+++ b/lib/worker/api/legacy_manifest_package.rb
@@ -19,6 +19,12 @@ module W3DHubLauncher
           @sha256_checksum = hash["checksum"]
           @checksum_chunks = hash["checksum-chunks"]
           @download_url = hash["download_url"]
+
+          # Fix crashing on spaces
+          if @download_url
+            uri_path = @download_url.split("/").last
+            @download_url = @download_url.sub(uri_path, URI.encode_uri_component(uri_path))
+          end
         end
 
         def error?
diff --git a/lib/worker/api/verification_data.rb b/lib/worker/api/verification_data.rb
new file mode 100644
index 0000000..d33e83a
--- /dev/null
+++ b/lib/worker/api/verification_data.rb
@@ -0,0 +1,107 @@
+module W3DHubLauncher
+  class Worker
+    class Api
+
+      # Cached verifcation data for application and pending package files
+      class VerificationData
+        SCHEMA = 0
+
+        def initialize(path)
+          @path = path
+
+          data = {}
+          if File.exist?(@path)
+            begin
+              data = JSON.parse(File.read(@path))
+            rescue JSON::ParserError
+              data = {}
+            end
+          end
+          data = {} unless data.is_a?(Hash)
+
+          @schema = data["schema"] || SCHEMA
+          @data = {}
+          data["data"]&.each do |key, value|
+            @data[key] = Data.new(value)
+          end
+        end
+
+        def key(file_name, file_version: "", package: false)
+          file_name = file_name.gsub("\\", "/").downcase
+
+          if package
+            "package:{file_name}:#{file_version}"
+          else
+            file_name
+          end
+        end
+
+        def data(key)
+          @data[key]
+        end
+
+        def unchanged?(key, checksum:, file_path:)
+          data = data(key)
+          return nil unless data
+
+          return data if data.checksum.upcase.strip == checksum.upcase.strip &&
+                         data.modification_time == File.mtime(file_path).to_i &&
+                         data.file_size == File.size(file_path)
+
+          nil
+        end
+
+        def set(key, checksum:, file_path:)
+          data = Data.new(
+            {
+              "checksum" => checksum.upcase.strip,
+              "modification_time" => File.mtime(file_path).to_i,
+              "file_size" => File.size(file_path)
+            }
+          )
+
+          @data[key] = data
+          save
+
+          data
+        end
+
+        def delete(key)
+          data = @data.delete(key)
+          save
+
+          data
+        end
+
+        def save
+          File.write(@path, JSON.pretty_generate(self))
+        end
+
+        def to_json(options = {})
+          {
+            schema: SCHEMA,
+            data: @data
+          }.to_json(options)
+        end
+
+        class Data
+          attr_reader :checksum, :modification_time, :file_size
+
+          def initialize(data)
+            @checksum = data["checksum"]
+            @modification_time = data["modification_time"]
+            @file_size = data["file_size"]
+          end
+
+          def to_json(options = {})
+            {
+              checksum: @checksum,
+              modification_time: @modification_time,
+              file_size: @file_size
+            }.to_json(options)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/worker/task.rb b/lib/worker/task.rb
index c9e33c8..67e778c 100644
--- a/lib/worker/task.rb
+++ b/lib/worker/task.rb
@@ -19,6 +19,8 @@ module W3DHubLauncher
 
       @status = Worker::Request::STATUS_PENDING
 
+      @verification_data = Worker::Api::VerificationData.new("#{CACHE_PATH}/verification_data-#{@application.id}-#{@channel.id}.json")
+
       # caching mechinism for file path normalization
       @file_index = {}
       # manifests!
@@ -32,6 +34,10 @@ module W3DHubLauncher
       # packages to verify and/or download
       @packages = []
 
+      # whether task should perform a per file checksum or just read it from the cache and
+      # check file modification time and size
+      @force_verification = false
+
       setup
     end
 
@@ -136,7 +142,7 @@ module W3DHubLauncher
 
       # Process manifest game files in NEWEST to OLDEST order so that we don't erroneously flag
       #   valid files as invalid due to an OLDER version of the file being checked FIRST.
-      @manifest_files.reverse.each do |file|
+      @manifest_files.reverse.each_with_index do |file, i|
         break unless File.directory?(@installation_directory)
 
         # skip irrelevant older versions of files
@@ -147,8 +153,15 @@ module W3DHubLauncher
         next unless File.exist?(file_path) # && !File.directory?(file_path)
 
         puts "verifying #{file_path}..."
-        checksum = cached_checksums[file_path] || Digest::SHA256.file(file_path).hexdigest.upcase
-        cached_checksums[file_path] ||= checksum
+        key = @verification_data.key(file.name)
+        pp [key, @force_verification]
+        verification_data = @force_verification ? nil : @verification_data.unchanged?(key, checksum: file.checksum, file_path: file_path)
+
+        # Use cached checksum if the file appears unchanged, otherwise recalculate it
+        checksum = verification_data&.checksum || Digest::SHA256.file(file_path).hexdigest.upcase
+
+        # Set or update cached verification data if files don't match
+        @verification_data.set(key, checksum: checksum, file_path: file_path) unless verification_data
 
         if checksum == file.checksum
           @required_manifest_files.delete(file)
@@ -159,6 +172,8 @@ module W3DHubLauncher
         else
           puts "  failed verification:#{file.version}"
         end
+
+        update_status(label: "Verifying files...", fraction: i.to_f / @manifest_files.size)
       end
     end
 
@@ -249,7 +264,7 @@ module W3DHubLauncher
         if manifest_file.patch?
           apply_patch(manifest_file, package)
         else
-          unzip(package_path)
+          unzip(manifest_file, package_path)
         end
 
         processed_packages[package_path] = manifest_file
@@ -265,6 +280,8 @@ module W3DHubLauncher
         if File.exist?(file_path) && !File.directory?(file_path)
           puts "Removing file: #{file_path}"
           File.delete(file_path)
+          key = @verification_data.key(manifest_file.name)
+          @verification_data.delete(key)
 
           remove_from_file_index(file_path)
         end
@@ -285,7 +302,7 @@ module W3DHubLauncher
       end
     end
 
-    # updated, and moved applications will overwrite existing application data in settings
+    # updated, repaired, and moved applications will overwrite existing application data in settings
     def mark_application_installed
       app = Worker::Api::Settings::Application.create(
         id: @application.id,
@@ -469,7 +486,7 @@ module W3DHubLauncher
         package_path = package_cache_path(package)
 
         puts "unpacking patch..."
-        unzip(package_path, f.path)
+        unzip(false, package_path, output_path: f.path)
 
         puts "reading patch data.."
         patch_mix = W3DHubLauncher::WWMix.new(path: f.path)
@@ -504,12 +521,16 @@ module W3DHubLauncher
           raise temp_mix.error_reason unless temp_mix.save
 
           puts "copying file..."
-          FileUtils.cp(temp.path, normalize_path(manifest_file.name))
+          file_path = normalize_path(manifest_file.name)
+          FileUtils.cp(temp.path, file_path)
+
+          key = @verification_data.key(manifest_file.name)
+          @verification_data.set(key, checksum: manifest_file.checksum, file_path: file_path)
         end
       end
     end
 
-    def unzip(zip_path, output_path = nil)
+    def unzip(manifest_file, zip_path, output_path: nil)
       stream = Zip::InputStream.new(File.open(zip_path))
 
       while(entry = stream.get_next_entry)
@@ -529,6 +550,23 @@ module W3DHubLauncher
           end
         end
 
+
+        # the manifest file we receive MIGHT NOT be for the current zip file entry
+        # so look it up to be safe
+        if manifest_file
+          manifest = @manifests[manifest_file.version]
+          if manifest
+            entry_manifest_file = manifest.files.find do |f|
+              f.name.gsub("\\", "/").downcase == entry.name.gsub("\\", "/").downcase
+            end
+
+            if entry_manifest_file
+              key = @verification_data.key(entry.name)
+              @verification_data.set(key, checksum: entry_manifest_file.checksum, file_path: file_path)
+            end
+          end
+        end
+
         add_to_file_index(file_path)
       end
     end
diff --git a/lib/worker/tasks/repair_application.rb b/lib/worker/tasks/repair_application.rb
index 68cf100..933d021 100644
--- a/lib/worker/tasks/repair_application.rb
+++ b/lib/worker/tasks/repair_application.rb
@@ -4,6 +4,9 @@ module W3DHubLauncher
       def setup
         super
 
+        # User requested a repair, make sure everything is as it should be!
+        @force_verification = true
+
         @task_verb = "Repairing".freeze
       end
     end
diff --git a/w3d_hub_linux_launcher.rb b/w3d_hub_linux_launcher.rb
index 59baa2b..0dc4dd2 100644
--- a/w3d_hub_linux_launcher.rb
+++ b/w3d_hub_linux_launcher.rb
@@ -60,6 +60,7 @@ require_relative "lib/worker/api/server_event"
 require_relative "lib/worker/api/test_event"
 require_relative "lib/worker/api/legacy_manifest"
 require_relative "lib/worker/api/legacy_manifest_package"
+require_relative "lib/worker/api/verification_data"
 require_relative "lib/worker/request"
 require_relative "lib/worker/w3dhub_api"
 require_relative "lib/worker/task"