stephan75: the API limit applies to all clients, whether P2, JOSM, Merkaartor or whatever.

Train2104: zoom in lots before editing. If you need to pan from one area to another, do it on the View tab (shows tiles) rather than the Edit tab (shows API data) by preference.

If you’re still having problems, you could ask on the IRC channel (http://irc.openstreetmap.org/) in case any of the sysadmins are around. Be prepared to give them your IP address.