With respect to all the thoughts and suggestions, surely with nothing beyond ‘feel’ to go on there is little point messing about with kit.
As has been mentioned, why not download Strava to a phone, place it in a pocket and go for the same ride on different bikes etc. If you make a note (say score out of 10 to make it quantifiable) of how you felt it went, both in terms of physical effort, comfort and enjoyment before you look at the Strava results, you’ll quickly be able to see what your dealing with.
It could be that one bike is a bit ‘dead’ in feel with the way it is built, which leads you to believe it is slow, yet in actual fact the data suggests otherwise.
Then when you have data to hand, you can combine all the info and decide if you prefer speed over comfort and quality of ride etc and if you then need to start swapping components to give you what you want out of a bike and a ride.