I also wonder what gear ratio you're using to accelerate in on the Trek versus the BMC. Obviously accelerating in a lower gear will make it easier.

Try riding both bikes back-to-back. Instead of acceleration which is hard to keep track of, try riding at a constant speed for a km or so. Use the same speed for each bike. Increase the speed each time and see how that feels. You will feel drag trying to maintain a high constant speed.

I hate to repeat this, but check the obvious things again like tire pressure, brakes rubbing, and crankset not turning freely. Remove the chain from the crankset so it can spin freely. Make sure it's not hard to turn. Remove the wheels and check the wheel bearings AT THE HUBS to make sure they feel ok.