Hello i'm on 1.16.4-forge-35.1.15 and using a chemical infuser with gas upgrades and speed upgrades uses a whole stack of salt to complete one shard but when i remove the speed upgrades it uses about 20 mb hydrogen chloride and the info says that using speed upgrades should increase efficiency of gases but im seeing the opposite

Gas upgrades increase efficiency, speed upgrades just increase the speed of machinery and in the cases of gas using machines especially where the gas is a secondary input for the most part they increase the cost of usage. In general you are probably better off setting up a system to create the chemicals rather than using direct item to chemical conversions as often the item to chemical conversions can't keep up/aren't as easily expandable.