When we went to AIX 4.3.3 we saw no problems
When we went from TSM server 3.7.2.0 we went (with a stop at 4.1.0.0 to pick
up license info) straight to 4.1.4.0 and we are now going to 4.1.5.0 based
on apar IC30347.
Our performance has always been good (same as before, maybe better) apar
IC30347 has to do with clients running multiple concurrent archives of files
from within the same directory...

Why was it only taken to 4.1.1.0 if it was performed a few days ago ??? the
4.1.5.0 has been available !
You might download the fix and look for changes in 4.1.[2,3,4&5] to see if
any address performance issues but in going from 3.7.2.0 to 4.1.4.0 I didn't
have any adverse effects (other than what is covered in IC30347) and I'm
about to correct that.

In our environments we keep a fast ethernet card running at 40+ GB/hr with
compressed client data
        with a GB interface we see about 56 GB/hr of compressed client data
(about 224 GB/hr of client SAP filespace)
our current cache hit % in that environment is Cache Hit Pct.: 98.90

hope this helps,
Dwight