Latency Proplem on Projects

I'm having a weird latency problem. On a couple projects there is a high amount of latency. If I create a new project and add a VSTi (VB3 or Kontakt2) there is NO latency problem. I'm wondering if I've changed a setting somewhere in the project. I'm fairly new to Reaper (not computers/DAWs,etc), but don't see where this could be coming from. I'm using the same ASIO settings in the existing projects and when doing the new project test. Some more details: - About 17 tracks 4 audio/ the rest VSTi - ASIO driver for Delta 24/96 set to 384 sample size, again this works fine in projects that I start new. - using VB3 ad Kontakt 2 primarily. (both exhibiting the problem) - Midi devices: the audiophile midi ports and an E-Mu XBoard. (both enabled) - I have the armed track set to Monitor Input and Record Input. Any Ideas? Of course this happened right after I bought a license.... Thanks for any pointers.

In the projects have you added a VST that you may not have used on the ones that are not giving you a problem?

Ahh - found the culprit. SIR impulse response reverb. Anyone else have a problem with that in Reaper? As soon as I bypass all is well. using version 1.011 on the master channel thanks for the info.

latency 

I notice that I get terrible latency if I have any FX on the master ch. while I try to record tracks. Fine during playback. And no I haven't had issues with SIR or SIR2.