One developer suspects that having an HDD and not an SSD, is an issue, but for me the problem is still in MT5 and in "what to do" to solve it in the code, because in MT4 there is NOT the same issue, and also the developer made me notice that while MT4 separate history files in hst for each timeframe, instead MT5 uses hcc files one for every year, not separated by timeframes. I supect that also behind this can hide the issue.
However, we haven't found a solution. I ask if someone who has experimented a similar issue can help or if anyone knows how to solve. Any suggestion is appreciated.