I haven't used the RT much as I gave it to my woman. but I haven't heard any IE11 complaints from her. so id assume its working fine. the times I did use it it seemed pretty fast.
as for your email syncing issue with gmail, I just looked at mines. go into your mail app, then click on your gmail account, then swipe from the right side in to bring up charm bar. then press settings. then accounts. click on gmail one. then in there you can set how often you want stuff to sync. I saw mines was set to arrive as they become available. but you can set that to like every 15 minutes, half hour, hour, 2 hours, etc...
now that I think about it, that's a great way to save battery. never realized I had it set to receive mail so often. im sure if I decrease the frequency of sync compared to immediate sync as new mail becomes available, itll improve battery life a lot.
thanks for bringing this up..haha