With swap files enabled (default setting), kate writes to the swap file after every change. On slow storage (like network disks) the text editor blocks sometimes for a fraction of a second (annoying). It would be nice if changes are written to disk only every x seconds and/or executed in a separate thread so that it doesn't block the text editor.
Network disks (eg NFS) are often synchronous (the data has to be written to disk before the write call returns, -similar to calling fsync after each write).
It writes to disk every 15 seconds, and if you check the option "[x] Disable swap files syncing" in Open/Save > Advanced, writing the swap file is never forced.
There was a bug in KDE <= 4.9, which got fixed for KDE 4.10: https://bugs.kde.org/show_bug.cgi?id=309751
So you need KDE 4.10. Does that work for you? I'll close this report as a duplicate of bug #309751.
*** This bug has been marked as a duplicate of bug 309751 ***