Writing in all capitals and red in an email is a pretty good way to piss anyone off. Sending an email that’s a duplicate of a forum post the recipient is going to answer anyway is also a pretty good way. We do this stuff for you for free, so be kind please.
From your all-caps email it’s hard to guess what the slowdown is. As I mentioned, I can capture HD frames at 30 fps from GrandVJ, even on a 2006 iMac.
The most likely cause is the disk not being able to keep up. This is quite likely if you are playing from and recording to the same disk. One thing to try would be recording to an external disk connected by FireWire (not USB).
Try a setup where the resolution is something reasonably small right through (the resolution in GrandVJ and Syphon Recorder, and the resolution of the clip you are triggering) – say 640×480 – and see what framerate you can achieve. If that works then try incrementally bigger frame sizes until you discover the limit.