It sounds like you are just used to the 'give' of the medium tension strings, with whatever combination you are used to of nail hardness, shape, length, and dynamic use of the three finger joints in the process of plucking a string.
You can verify that it is the tension difference on your Soloette (with the medium tension) where you feel comfortable playing fast. Try moving your right hand a few centimeters towards the bridge and play again the same passage. This will simulate 'higher tension' strings because it will feel harder to displace the strings because they are stiffer.
If so, you'd have to adjust your stroke for the higher tension strings - trajectory, impulse force, how stiff or loose your tip joint is; how deep your fingertip sits when prepped on a string before a stroke; nail length and shape adjustments if needed - so that you start performing a stroke which, relative to the string, resembles what happens when with the medium tension strings. This should result in a measurable improvement in ease.
I personally went through something similar a couple of years ago in order to be able to play with ease on Savarez Cantiga/AllianceKF high tension because I really liked their brilliance and feel. It is doable; there is nothing inherent in high tension strings that makes one get stuck and not able to play fast.
1982 Anselmo Solar Gonzalez