Perfomance poor after upgrade

Hi, after having upgraded till latest version of DraftSight the performance is significatly poorer than on the old version. We are running a classrom set of relatively old machines.

We have tried to upgrade display driver and RAM, but so far this has not given the result we were hoping for.
"Downgrading" to the previos version is not realy an option as we have installed the new license sever system.

Any suggestion to what to try to solve this issue are will be highly appreciated.