How 'heavy' is it on the server to run mysql commands every few seconds

I have a set of data that is used by GUI for positions and stuff, and that positions are also stored in MySQL. Every time the data changes, it is reflected on the server too.

Then if I want to update MySQL as frequent as jquery (or javascript, I don't know) tracking "mousemove" motion, that is, send request to the server that for every "mousemove" change the value in MySQL, how 'heavy' is it, especially when multiple users are using the same server?

What would be a better solution? I'm thinking of waiting for 3 seconds until the motion is finished, then if there is no more motions, sending request to the server then.

Although multiple people aren't using my server, but this always concerns me and hinders me from progressing. Please help.