I have problem with ftp connection on SCO UNIX 5.0.7, it is work slowly. How I can
make accelerate.

Is it slow to logon? Is it the transfer rates? Can you be more specific, if it is logon you could try creating a .netrc file on the server you are using to automatically logon, and be sure the server(s) you are connecting to are in the hosts file on the server you are using. This would of course depend on what you speed issue is and when it is happening.

It is slow to logon.

What OS is on the source and the destination?
If you are using a local connection, make sure that the hosts file on both machines is correct.
If it is an internet connection, do a 'traceroute(unix)' , or 'tracert(windows)' to see how many hops are needed to get to the destination.
Are you using DNS, or the IP address as the destination, is the response the same both ways?
Do you have the same slow response if you use telnet or ssh?
Do you have the similar results with other destinations?

Source OS is Windows XP destination OS is SCO UNIX 5.0.7. when source is UNIX and destination is UNIX it is not slow.
It is local connection.
I am using IP address.
Hosts file on both machines is correct.
I have the same slow response if use telnet.

Have a good look at ip addresses and netmask settings on both.
Are both machines connected to the same hub (concentrator)?
I tried copying files from a SCO 5.0.7 computer to a Win2K client, on a 100mhz network and got the following results:
Time to get login prompt 2-3 seconds.
Transfer rate 10mb per second.

Both machines are not connected to the same hub (concentrator).
Time to get login prompt is 10-15 seconds.