In Thunderbird 31.5.0 I noticed an annoying mouse delay/stutter when mousing over the email list or folder pane. At the same time I see a CPU spike of about 25% (older WinXP dual core system).
Why is this happening / what can I do to optimize thunderbird for older systems?
( Update 9/2015: Also noticed this on Firefox and was able to fix it in about:config using the same layers.acceleration.disabled = true )