eValid, like any browser, will have a growing footprint that increases in size the longer it is in execution and the more pages that are visited.
In LoadTest mode, when you are most likely using the "THIN" version of eValid -- the one optimized to have both minimum initial footprint and to have mininmal growth in footprint size -- you still will see growth over time. As far as we can tell this is the nature of browsers; we can't do anything about it (but the fact of THIN's existence does say that we have tried, and continue to try, to reduce footprint growth).
But there is a kind of workaround for this: There is a setting in eValid LoadTest mode that forces an automatic re-spawn after a fixed (user specified) number of playbacks. This means that the entire eValid instance is zapped and a new instance is put in play doing the same work.
There's a small overhead for doing this, because eValid just collapse and then relaunch.
We have found that a re-spawn rate of 10 or 20 or 50 seems to be a good compromize between running out of RAM (and the consequent memory thrashing) and the overhead of restarting the Browser User in the middle of a performance test run.
eValid LoadTest Support