Summary of changes in Tp data from bug 449356: pre-449356 post-449356 change (ms) change (%) new (large) page set: mean 1st page load 583 439 -144 -25 mean median page load 427 425 -2.5 -0.6 old (small/fast) page set: mean 1st page load 480 345 -135 -28 mean median page load 237 257 +19.2 +8 Note that talos loads each page in the page set, then cycles through the same set another 9 times. The "mean first page load" data comes only from the first run through the page set. These numbers are representative of viewing a page from a new site, and closer to representative of zooming a page. Talos normally reports the medians. The "mean median page load" is the result of taking the median over all 10 cycles for each single page, then taking the mean over all pages. These numbers represent a cached page load time and are representative of reloading the existing page or viewing a page with very similar fonts (probably on the same site). Most of the numbers here are improvements, and when also considering the Ts and Tp_RSS gains, we're heading in the right direction. The one number is worse is the cached page load time for the old page set. This is an indicator that there is room for improvement here. These pages are such that the fonts used when reloading the page were almost always found in 5000 entry gfxPangoFontCache (see bug 424622 and bug 428425), which we no longer have. The gfxPangoFontCache used several megabytes of memory, but I imagine we could achieve similar (or better) reload performance with a much smaller gfxFontGroupCache with font groups expired based on time. I've filed bug 463576 on this.