hi,

why is this? is it something to do with potentially overloading the system or something else?

thanks

Yes. What if, for some reason, this applescript doesn't finish in a minute? Then you have a second copy running. If that causes further slowdowns, then you could end up with a quickly escalating system problem.
This constantly forking process that is calling applescript could cause lots of unexpected results in your battery life, or your interface response time. Your system being distracted by running this process under the Finder could have lots of unexpected results.

I actually think posting this as a hint on the site is sort of irresponsible.