@"TM2YC" , have you tried using the time remapping tool? You may need to adjust your animation range due to the new speed, but I believe it will allow you to achieve the speed you are looking for.
The time remapping is like a ratio. You'll see that 100 vs 115 is relatively the same as it's only 1.15x slower. You can change the Old to something like 10 and the New to something like 20 which will create a 2x slower effect. Finding the right ratio of old frames to new frames should result in the speed you are wanting to achieve.
Here's another video that explains the concept.
p.s. if you find the magic ratio, please share