Whenever I start my local ssh login I have to wait for seconds to write a complete command. Even "ls" is taking so much time.
I am using it wireless with two of my linux laptops and connecting to my college wifi network.
...high latency like this can happen.
Besides that, and perhaps some other conditions I haven't thought of, this isn't normal--not when SSHing from one local machine to another using the server's local name or IP address. (If you're connecting through the router so it's as though you were connecting over the Internet, but bouncing back to the SSH server, that might be a different story. This will happen if port forwarding or NAT-based DMZ is set up to the SSH server and you access it through its WAN--i.e., Internet-facing--hostname or IP.)
So more troubleshooting would be a good idea. You may want to start by expanding your question with details about whether or not anything else is slow over this network.
One thing you can try now to increase performance is to use the Blowfish cipher with SSH. So if you're currently running:
You'd run this instead:
Blowfish has a reputation for computational speed, and I've seen speed improvements with it in SSH on some systems... but I don't know if it's actually the fastest (of all sufficiently secure) ciphers supported. Perhaps someone knowledgeable about these matters can post another answer that goes into more detail about cipher choice.
You can enable compression too (with the capital