low latency - aud.ini settings for plugins?

Hi,
 
I'm just experimenting with a new audio interface (MOTU Ultralite AVB - see this thread http://forum.cakewalk.com/MOTU-Ultralite-AVB-m3190029.aspx ). I can get down to 7.8ms RTL without too many crackles etc - but I'm really struggling to get it down to the lowest (4.9ms RTL) unless I'm only running a couple of tracks.
 
My audio tracks are all guitar - with the S-Gear amp sim, and maybe a few more FX on some. If I disable all plugins, I can get a lot of audio tracks running at the lowest latency. With all the amp sims running (and of course the CPU is higher, but not *that* high) - there are mucho crackles.
 
I don't know if the plugins are causing this, or if it's CPU usage (it's not really going over 50% on th efirst core, and less on the others) - or if my PC just isn't going to go down to the lowest latency.
 
It's not really a big deal - as I'm quite happy at the little bit higher latency - but I'm just wondering if there is anything I can play around with in AUD.INI that might help?
 
I've played with latencymon etc, and there aren't really any problems with background services running etc - these crackles are either there all the time or they aren't.
 
As I said, if I can't go down to the lowest setting, I'll forget abvout it - and get back to making some music - I'm just wondering if anybody has any ideas for things to try?
 
Thanks...

Hi Jim,
 
DPCLAT (which may be deprecated for 64 bit Windows) shows mostly littly tiny latencies <10us - with occasional blips (still green) up to 500us or so.
 
LatencyMon shows the highest at 100-200us (.1 - .2ms) This si mostly for the USB port, but there are some for NDIS, and "network" things. I can disable the network card - but that doesn't help get rid of the crackles at 4.9ms RTL. I would go after this if I was getting "some" or "occasional" crackles - but I think my PC just might not be able to go that low.
 
As I said - 7.8ms RTL works OK, and it's good to know that the Ultralite AVB has the *potential* to go that low (ie next PC) - but I'm keeping my eyes open for things to try with this setup ;-)