This is with ESftp 1.1.1 in Eclipse 3.3.2 build M20080221-1800 under Windows XP Pro SP3. I have experienced the same problem using numerous other versions and builds of Eclipse.
After ESftp downloads a remote directory of any appreciable size (say, a few hundred files/subdirectories), Eclipse completely locks up (using 0% of the CPU) and never comes back. The only thing to do is to force-quit Eclipse.
I believe the lockup occurs at the end of the download, when ESftp/Eclipse starts parsing/scanning the files it has downloaded. That's little more than a guess, though.
It happens every time. I don't know whether it's the number of files/directories, or their combined size, that causes the problem, but I suspect the former - I've never noticed the problem while transferring individual large files.