Spectrasonics has posted an update for Stylus RMX.Version 1.8.2d is a minor one, but improves RTAS performance among other things.

From Spectrasonics:

Contains the following changes:

• Loading a midi learn template now clears current assignments.
• Improved timing precision in RTAS version when using very large audio buffer sizes.
• Changed Time Designer templates so they have an effect when non-Main edit group selected.
• Improved graphics performance with some video cards.
• Fixed Flame Distortion in 64 bit version of plugin.

In a thread on Gearslutz, Spectrasonics also stated the following, suggesting improvements not stated in the list above:

We just released the v1.8.2d update which improves RTAS performance quite a bit and now works with multi-processor support much better with Pro Tools 8, etc.

Spectrasonics