diff --git a/app/controllers/projects/pull_requests_controller.rb b/app/controllers/projects/pull_requests_controller.rb
index 34c8c6f0f..f1b0139d4 100644
--- a/app/controllers/projects/pull_requests_controller.rb
+++ b/app/controllers/projects/pull_requests_controller.rb
@@ -128,16 +128,15 @@ class Projects::PullRequestsController < Projects::BaseController
   end
 
   def load_diff_commits_data
-    @repo = Grit::Repo.new(@pull.path)
     @base_commit = @pull.common_ancestor
-    @head_commit = @repo.commits(@pull.head_branch).first
+    @head_commit = @pull.repo.commits(@pull.head_branch).first
 
-    @commits = @repo.commits_between(@repo.commits(@pull.to_ref).first, @head_commit)
+    @commits = @pull.repo.commits_between(@pull.repo.commits(@pull.to_ref).first, @head_commit)
     @total_commits = @commits.count
     @commits = @commits.last(100)
 
-    @diff = @pull.diff @repo, @base_commit, @head_commit
-    @stats = @pull.diff_stats @repo, @base_commit, @head_commit
+    @diff = @pull.diff @pull.repo, @base_commit, @head_commit
+    @stats = @pull.diff_stats @pull.repo, @base_commit, @head_commit
     @comments = @issue.comments
     @commentable = @issue
   end
diff --git a/app/models/comment.rb b/app/models/comment.rb
index ff1e0f802..61aabdef9 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -93,10 +93,8 @@ class Comment < ActiveRecord::Base
     return true if params[:path].blank? && params[:line].blank? # not inline comment
     self.data = {:path => params[:path], :line => params[:line]}
     if commentable.class == Issue && pull = commentable.pull_request
-      repo = Grit::Repo.new(pull.path)
-      to_commit, from_commit = pull.common_ancestor, repo.commits(pull.head_branch).first
-
-      diff = pull.diff repo, to_commit, from_commit
+      to_commit, from_commit = pull.common_ancestor, pull.repo.commits(pull.head_branch).first
+      diff = pull.diff pull.repo, to_commit, from_commit
       diff_path = diff.select {|d| d.a_path == params[:path]}
       return false unless actual_inline_comment?(diff, true)
 
diff --git a/app/models/pull_request.rb b/app/models/pull_request.rb
index 41f1e8c5c..d6148580a 100644
--- a/app/models/pull_request.rb
+++ b/app/models/pull_request.rb
@@ -96,7 +96,6 @@ class PullRequest < ActiveRecord::Base
 
   def common_ancestor
     return @common_ancestor if @common_ancestor
-    repo = Grit::Repo.new(path)
     base_commit = repo.commits(to_ref).first
     head_commit = repo.commits(head_branch).first
     @common_ancestor = repo.commit(repo.git.merge_base({}, base_commit, head_commit)) || base_commit
@@ -147,6 +146,10 @@ class PullRequest < ActiveRecord::Base
     end
   end
 
+  def repo
+    return @repo if @repo.present? #&& !id_changed?
+    @repo = Grit::Repo.new path
+  end
   protected
 
   def merge
@@ -204,8 +207,7 @@ class PullRequest < ActiveRecord::Base
 
   def update_inline_comments
     if self.comments.count > 0
-      repo = Grit::Repo.new self.path
-      diff = self.diff repo, self.common_ancestor, repo.commits(self.head_branch).first
+      diff = self.diff self.repo, self.common_ancestor, repo.commits(self.head_branch).first
     end
     self.comments.each do |c|
       if c.data.present? # maybe need add new column 'actual'?
diff --git a/app/views/projects/pull_requests/_pull_diff.html.haml b/app/views/projects/pull_requests/_pull_diff.html.haml
index dc707a042..931084e7e 100644
--- a/app/views/projects/pull_requests/_pull_diff.html.haml
+++ b/app/views/projects/pull_requests/_pull_diff.html.haml
@@ -6,5 +6,5 @@
     - if pull_diff.b_path.present?
       .r= link_to "view file @ #{short_hash_id(commit_id)}", blob_path(@project, commit_id, pull_diff.b_path)
     .clear
-  -if pull_diff.diff.present? && !(Grit::Repo.new(@pull.path).tree(commit_id) / pull_diff.b_path).binary?
+  -if pull_diff.diff.present? && !(@pull.repo.tree(commit_id) / pull_diff.b_path).binary?
     .diff_data=render_diff(pull_diff, pull_diff_counter, @comments)