scalability of dictionary based compression

Could anyone please share some information on performance constraints
in dictionary based compression algorithm in real applications such as
PPP communications, for example the maximum number of simultaneous
sessions, the largest dictionary size for each session, usually
compression/decompression speed, etc? I wonder whether the
compression/decompression would be a performance bottleneck for such
applcations to support a large number of simultaneous sessions.

Thanks in advance,

G.