Hi syntho,
I don't know if the following will help you, but maybe it is worth a try:
I have these slow meters when I use Softsynth-RTAS plugs (like Kontakt, Battery ...) connected via DirectConnect and an IAC Driver. When I HAVE NOT opened the application (for example Kontakt ...) which is at the moment used by a open Protools File and directconnect, the meters slow down extremely!!! In the moment when I open the "missing" application (Kontakt) and the DirectConnect-connection is established again, the meters behave normally.
Hopefully this is a help for you,
paule.