At bug 1181907 comment 90 and 91 I noticed that TART reports practically identical numbers for newtab-open-preload-no.all and newtab-open-preload-yes.all. However, when testing locally manually (just opening new tabs with ctrl-t), it seems to me that the animation is better with preload. ttaubert seems to agree. Investigate why TART doesn't show a meaningful difference. The attachment shows graphs of the 25 replicates of a single TART run for win7 opt on cset 07ff9769e2023dcc8a07f5e7df0febb05c82a446 . Notice the very similar values between newtab-open-preload-no.all and newtab-open-preload-yes.all (and ignore simple-open-DPI1.all).
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