What does the "Bitmap Caching" option do in the Remote Desktop Client?

"Caching bitmap means that images and other bitmap resources are locally stored on the client computer for reusing them later. This way, the remote server or PC doesn't send images twice reducing the amout of data sent and saving your bandwidth usage.

The option makes particularly sense for slow (low bandwidth) connections, less if you connect to a machine in the same local area network.

If you enable the option the Remote Desktop client caches bitmaps into a BMC file located on the client hard disk in (example for Windows XP)

C:\Documents and Settings\<username>\Local Settings\
Application Data\Microsoft\Terminal Server Client\Cache

folder.

Note (interesting if your computer is part of a domain): since the cache folder is stored in a ""Local Settings"" folder, it won't be replicated as part of a roaming user profile."

"Since RDP relies on transmitting paint commands to the client, instead of just raw pixels from the virtual screen, eventually paint commands will come that say ""Paint this bitmap on the screen"", and for those commands, a copy of the bitmap will be sent to the client as well.

That setting will cache the bitmaps for those commands, so that the next time a command comes with the same bitmap, the bitmap doesn't have to be transmitted. This speeds up the RDP protocol a lot over a slow connection."