Quick update: It definitely helped, but setting fsend 100, will also make the connection unstable, I tried at 50, and my speed improved a lot, but still a little unstable, I will try different settings and bots to test properly smile

That is not too surprising. The higher the value, the more likely that the large number of transfer events/messages will overwhelm the processing of other windows events/messages in the single main thread. As well as affecting the GUI, this could affect other features. This change in /fsend is entirely experimental. If it works for you, great. If it does not, there is no other option at the moment to make transfers fully utilize 100Mbit connections I'm afraid.