1 maxclient general consumes about 15MB ram. Depending how many modules you have installed. But if you set your keepalive to 2 seconds. The user will only use the ram for 2 seconds, then it closes the client. (The default is 300 seconds , which is 5 minutes!)
Its not just Glype - all proxy scripts will do this if you are getting lots of traffic to your proxies. As long as you have enough RAM you can increase the amount of MaxClients. Generally you divide your RAM by 5 to get to approx. how many MaxClients you can have.