Large Bookmarks.plist file makes Safari v. laggy

[theorist9]

When I use a "clean" Bookmarks.plist file, Safari is very responsive -- new windows open in ~<=0.3 sec., and the window resizes smoothly and rapidly when I drag it with the cursor. But with my regular 640 KB Bookmarks.plist file (2800 items), the program becomes very laggy -- it takes a second or two to open a new window (even if I have it set to open an "empty window"), and there's stuttering when I resize the window.

I've cleared out all my Safari history and caches (basically everything except my passwords and bookmarks), did an SMC and PRAM reset, and reinstalled Yosemite, yet Safari is still very laggy for me -- the only thing that fixes this is switching from my original Bookmarks.plist file to a clean one; so I'm reasonably sure that's the culprit.

Any idea of why this is happening, or what I might do to fix it? I did a screenshare with a senior Apple advisor, and he could see that the difference with-vs.-without the file was striking, and said he had never heard of this. He promised to consult with the engineers, but in the meantime I thought I'd see if the collective expertise here might be able to help.

System info.: Yosemite 10.10.3, Safari 8.0.5
MBP 11,3 (15" Retina, Feb 2015), 2.8/4.0 GHz Core i7-4980HQ, 1TB SSD/4-lane PCIe, 16GB RAM

 

[Weaselboy]

Just an idea, but worth a try.

Go to the Safari File menu and toward the bottom select Export Bookmarks... and save that to the desktop. Then quit Safari and delete the bookmarks.plist file and launch Safari. This should give you a blank plist with default bookmarks. Now go back to the Safari file menu and import the bookmarks from the HTML backup we made earlier.

That will hopefully get you a clean plist with your bookmarks in there.

 

[theorist9]

Thanks, your suggestion was quite helpful in enabling me to figure out the problem. I tried what you suggested and it was much faster, but only because the favorites were imported into a subfolder and thus not displayed in the favorites bar. Once I imported them into the main list of favorites, the behavior returned. This was very helpful, because it enabled me to pinpoint the issue:

It's not the presence of the large Bookmarks.plist file itself. Instead, it's about 75% from displaying the Favorites Bar and 25% from having new windows open with the Favorites. Even while keeping the large Bookmarks.plist file, here's what I find for responsiveness:

Favorites Bar + new Window opens with favorites: really slow
Favorites Bar + new Window is empty: still pretty slow
No Favorites Bar + new Window opens with favorites: fairly fast
No Favorites Bar + new Window is empty: really fast

 

[theorist9]

I just tested this with Firefox and Chrome, using the same set of bookmarks. Both show the same qualitative behavior as Safari in the presence of the favorites bar. HOWEVER, while Firefox slows down about as much as Safari, Chrome is only slightly slowed.