It's probably just a coincidence the data slowed after you flashed it. VM's 3G data is flaky and varies by location and time of day. Maybe you can try a re-wipe and reflash if it doesn't improve in the next few days.
It's as smooth as a baby's bottom, as for Froyocream, I'm not sure. It does have pretty good optimizations (debugging turned off, SIO scheduler). I run 61-1024 Mhz interactive governor and notice no hiccups (except when Android is doing heavy app installing/loading in the background).
Yeah GPS is a hit or miss. Not even sure if the gps.conf file makes any difference since TG mentioned aGPS has never worked on the MT, even in stock.
I have a new kernel that might fix the touchscreen reliability (it bugs the hell out of me personally, and I could probably recite the bi041p_ts.c driver source from memory by now). Here it is if anyone wants to flash & test the latest possible fix. Let me know if you notice any improvements or not. It only occurs rarely & randomly, so hard to test.
WhyKernel -01-16.zip