I think you shouldn't bother with this until you have your actual application working and you realize that this is an issue.

Otherwise, what you are suggesting falls into Premature Optimization; I would recommend following YAGNI principle here and work on this buffering topic when it becomes an issue. There's an idiom involved: you'll cross that bridge when you come to it.

In Delphi, few years back they have integrated fast memory manager which should suffice for even more demanding server/client applications. In any case, I don't think you'll have to worry about memory fragmentation and buffer usage.