First of all.. I saw your post some time ago but I really don't have any good idea "how to fix it" so i didn't posted. Cause nobody answered you i'll try my best.
I got same problem with my old ati radeon 9200 while i was using official drivers. When I switched to omega drivers(there are no versions for new gfx cards from what i heard) all worked well. My friend with radeon 9600 got fps loss while hovering over object in editor(from 110-120 to 3-5).
With my current gfx card(radeon 3850) I have big problems with editor too (none in normal game). Fps are awkwardly low for my gfx card (around 40-80 on empty map-got same fps with radeon 9200). I tried to create some new cool map with triggers and stuff but editor is just crashing randomly(6 crashes in 10min). So I just dropped my idea of new map
1. I read somewhere here on forums that editor crashes on Radeon graphic cards if you dont have "ati catalyst control center" installed. I installed it some time ago thru I didn't checked if that fixes editor crash.
You could try to install it if you dont have it yet. If that won't solve your editor problem then try to use newer/older drivers for you graphic card(if there are any..).
2. Try running savage in administrator mode if you are on vista. I think that there was similiar topic/post about that problem. I don't remember if there was any fix for it or not.
You could try to redownload savage xr(without rmod) and check if you have same problem(I dont think its rmod fault).. or try sfe.. It would be cool if you could post if you have same issues on sfe.
Good luck. I hope this helps a bit