Created attachment 336 [details]
In version 4.1.20-6, the simulation graph has label of the x-axis consists mostly of "invalid character" characters. It should show "time".
I have attached a MWE, where you first check the query, right click and choose "Simulations (1)". Additionally, I have attached a screenshot showing the incorrect label.
Created attachment 337 [details]
Yes, there is a memory issue, thanks for the report.
We are working on it.
This has been fixed and released in stratego-7