Different Backtesting vs Forward Testing Speed


Can some please help me with this issue.

I purchased a workstation with two 22 Core Xeon processors( total 88 individual agents) to speed up my MT5 EA testing. I usually do a backtest + forward optimization. I have noticed that during the backtest, all the 88 agents are used but during the forward test only some are used, slowing down the process. I do not understand why all the agents are not used for the forward test as well.