It seems very unlikely that it is the accumulation of data that is causing the problem. For most people, the experiment handler is just storing a relatively small amount of text/numeric data per trial, which isn’t going to tax your computer’s memory.
But somehow you seem to have isolated the memory memory leak to the ExperimentHandler? If that is the case, I wonder if you are inadvertently storing some of your actual sound stimuli within the ExperimentHandler, rather than just the names of their associated files? I tried to look at the code for the minimal reproducible example you posted here:
but unfortunately that link is no longer live.