there are three things to fix here 1. the panel loads slowly, sometimes a full second before it shows 2. the thumbnails load slowly - sometimes i get empty panel, then thumbnails fill in 3. the panel leaves slowly, sometimes stuck there for half-second

(In reply to comment #0) > there are three things to fix here > > 1. the panel loads slowly, sometimes a full second before it shows Maybe you're seeing the intentional effect of bug 498272? > 2. the thumbnails load slowly - sometimes i get empty panel, then thumbnails > fill in > 3. the panel leaves slowly, sometimes stuck there for half-second I don't think I'm seeing this on Windows and Linux. Could this be a Mac-specific regression?

(In reply to comment #1) > > 1. the panel loads slowly, sometimes a full second before it shows > > Maybe you're seeing the intentional effect of bug 498272? If so, we need to tune it. It feels *really* heavy. I'd describe it as laggy actually. > > 2. the thumbnails load slowly - sometimes i get empty panel, then thumbnails > > fill in > > 3. the panel leaves slowly, sometimes stuck there for half-second > > I don't think I'm seeing this on Windows and Linux. Could this be a > Mac-specific regression? I'm on Win7. Note that these perf issues are not 100% of the time I use it. However, it's often enough to be pretty serious bug IMO.

(In reply to comment #2) > (In reply to comment #1) > > > 1. the panel loads slowly, sometimes a full second before it shows > > > > Maybe you're seeing the intentional effect of bug 498272? > > If so, we need to tune it. It feels *really* heavy. I'd describe it as laggy > actually. In order to find a better default value, we could add a hidden pref or if you're building on Win7 you could modify the number directly: http://mxr.mozilla.org/mozilla-central/source/browser/base/content/browser-tabPreviews.js#379 > > > 2. the thumbnails load slowly - sometimes i get empty panel, then thumbnails > > > fill in > > > 3. the panel leaves slowly, sometimes stuck there for half-second > > > > I don't think I'm seeing this on Windows and Linux. Could this be a > > Mac-specific regression? > > I'm on Win7. > > Note that these perf issues are not 100% of the time I use it. However, it's > often enough to be pretty serious bug IMO. I'm on XP. On Win7, the only difference from our side is that we're using Aero Glass. I guess you could try launching Minefield in XP compat mode and see if this makes a difference.

For the slow mouseover feedback performance I've found that removing display:block makes it a lot faster. Maybe we'll have to reimplement the wrapping in JavaScript - mixing display:block with XUL doesn't seem to work very well.

That's interesting, but now we're talking about a different panel. One opens when pressing Control+Tab (pref: browser.ctrlTab.previews) and another one can be opened from that panel or via Shift+Control+Tab or with the All-tabs button on the tab strip (pref: browser.allTabs.previews). Now I'm not sure which one you meant, Dietrich.

I filed this bug on ctl+tab, not the all-tabs panel.

Ok, comment 4 is about the all-tabs panel unless I'm missing something.

Yes, sorry I wasn't paying attention.

I can't reproduce sluggishness in the ctrl+tabs panel on a modern MacBookPro. nor on an 6 y/o XP box. Has other work in this area somehow addressed the initial issue, dietrich?

I'll re-test next time I boot into Windows.

This is still an issue. Compare opening and closing multiple tabs very quickly on Chrome and Firefox on Mac OS X. I have a 2012 MBPro Retina. Firefox is very slow. It's really the last thing that is keeping me from switching back to Firefox. I am willing to record a video.

(In reply to Bjorn Tipling from comment #11) > This is still an issue. Compare opening and closing multiple tabs very > quickly on Chrome and Firefox on Mac OS X. I have a 2012 MBPro Retina. > Firefox is very slow. It's really the last thing that is keeping me from > switching back to Firefox. I am willing to record a video. It sounds like you're not actually experiencing the issue this bug was filed for. Can you file a new bug?