From the very beginning, performance has been a significant problem with remote control software. On the early programs, everything from screen updates to keystrokes was agonizingly slow, making remote troubleshooting a frustrating experience for technician and user alike.
While performance has improved, don’t expect full-speed responses on either computer, especially for I/O operations such as mouse commands and screen updates.
Many of the remote control products, especially the commercial ones, have features built in to speed things up. For example, UltraVNC has the ability to read the target computer’s graphics frame buffer directly to update the remote system’s screen more quickly.
One result of all this delay is that there’s a certain "feel" to every remote control program; the people who use these programs frequently, such as the Help Desk folks, need to adapt themselves to the program’s feel. For example, if the program’s mouse response is slow (or, worse yet, variable), you might find yourself bouncing the pointer all over the screen until you get the hang of it.