Limit effect not rendering in real-time?

[ejdge]

I'm having the LE to render in RT in the canvas. Every other effect renders real time in preview (green) except this. I'm coupling it with the 4/8 way matte boxes but everytime I start adjusting the saturation/luminance, it requires me to render to view the effect. This makes color correcting very hard when using these. Any ideas?

Here are my settings
Unlimited RT
Playback Quality/Frame rate- Dynamic, Dynamic

Footage captured at HDV 1080 24p- Shot in HD on a Canon A1-XH at 24f

Here's my system specs
Mac Pro
2.66
7300 gt
3 gb ram
250 gb glyph external hd