lsof runs very slow in my server
Solution 1:
If you are certain that you can skip the open TCP or UDP connections, since you mentioned there are too many of them, you can use the dialect-specific option of lsof -X.
lsof -X
Read the man page of lsof and search for '-X' for detailed information.
Solution 2:
Pass the -n option to skip resolving DNS names of IP connections. This will almost certainly be the biggestion portion of any slowdowns.