Complex sentence: The main disadvantages of a speed reload are that if there are rounds left in your ejected magazine, you will lose them, and it is much louder than a tactical reloads and leaves the magazine and bullets as evidence.
Split into simpler sentences: The main disadvantages of a speed reload are that rounds left in the ejected magazine are lost. Additionally, performing a speed reload is much louder than a tactical reloads and leaves the magazine and bullets as evidence.