Logic 9's UI extremely laggy - any fixes?

I've been a pretty happy Logic user since 2004, but lately version 9 has been really cheezing me off. It seems that whenever I'm playing my current project, the user interface becomes completely unresponsive to key commands and mouse clicks, which will be delayed for many seconds, or ignored entirely.

This is a fresh install of Logic Pro 9.1.4, 32-bit, on one of the new Mac minis (dual 2.7GHz i7, 4GB RAM, stock 500GB hard drive), with a PreSonus FireStudio Project. However, this was also happening on my previous system, a 2008 15" unibody MacBook Pro. It was happening a little bit on Snow Leopard but it's gotten much worse under Lion. My MacBook had aftermarket RAM (8GB) and an aftermarket SSD, but everything in the Mini is stock.

It's happening even if I only have one or two tracks, although it seems to be worse if I have any of the various metering plugins running and open, or ChanEQ with the analyzer turned on. I wonder if maybe those plugins aren't handling UI updates correctly, or something.

Just to be clear, I have absolutely no third-party AudioUnits installed, and it's neither a CPU nor an I/O issue (both gauges are pretty much empty, and Activity Monitor shows Logic as taking about 10% of one CPU), and yet it takes anywhere from 3-10 seconds for a simple mouse click to go through.

This is getting EXTREMELY frustrating, especially since the lag seems to always happen at the worst moments (i.e. I'm trying to turn down the volume on a track which suddenly got really loud, and the lack of responsiveness means my ears get blasted and I have to take a break for them to recover before I can start mixing again).

Has anyone else been experiencing this and found a workaround? Is anyone at Apple even paying attention to these issues? I feel like it's the same problem that was being discussed in this thread, which was never resolved: https://discussions.apple.com/thread/2396951

Message was edited by: robert113