i've eperienced some small "lags" on the above mentioned map (mostly after the start, and no, other maps didn't have those lags), a look into the ufoconsole.log showed hundrets of error messages like this:
"Too many particles (don't add burnFlame2) - exceeded 2048
PC_SPAWN: Could not spawn child particle for 'crashsite_fire'"
r26164
Win 7 x86 RC, Geforce 9600M GT, Core 2 Duo P8400, 4GB RAM (or 3.xGB <- 32-bit)