best packet compression method

Hello to all you compression experts.

First , By best I am reffering to best compression ratio.
comppression time should be fast , but not necesseraly extremely fast
.
Second , I want a generel purpose compression with emphasis on good
text and
Multimedia compression.
Third , data to be compressed is IP packets (size up to 1.5K ) .Which
can consist all kind of data ,including text and multimedia .
I can't use a buffer to store a lot of packets since It has to be done in very small delay .
I can't parse the packets content to determine it's contents , since it would most probably be wastefull in terms of cpu usage (and is technicaly not trivial ) ,
I have been reviewing and testing a few algorithms and combinations .
I have tried BTW + LZ (+MTF+RLE+HUFF) . But the sorting doen't give
good results on small blocks .
I have tried PPM+reduced offset LZ . a combination that compresses
extremely well on the expanse of High memory and cpu usage .

to make a long question short :
I am looking for ideas on how to achieve a best compression on a IP
packet stream .
any suggestions would be welcomed !

thanks ,
yosi .