XLIB Programming Manual, Rel. 5, Third Edition

5.9 GCs and Server Efficiency

Some servers can cache a limited number of GCs in their display hardware. These systems achieve highest performance when the number of GCs created by an application is less than the number that can be cached at one time. Furthermore, each GC takes up some amount of server memory. Therefore, it is a general principle that an application should create as few GCs as reasonably possible.

However, this should not be taken to extremes. For example, all applications could be written to use only one GC, changing it frequently every time different characteristics are needed. But this defeats two of the purposes of the GC, which are to reduce network traffic and simplify programming. There are also performance costs when GCs are changed too often.

Deciding how many GCs to create and when to change them is a trade-off between the benefits of a more efficient server against the benefits of reduced network traffic and simpler programming. The designers of X still think that using a small number of GCs is, overall, the best approach.