That 3-point bar actually does something for performance as opposed to NVH reduction and maybe improved steering feel. You're getting some triangulation back to the firewall, assuming that it was done up properly. The problem you're trying to solve is chassis torsion, which is a 3-D structural problem that isn't going to be helped much by a brace that only connects straight across in one transverse plane (and is typically only bolted to the strut towers at the strut attachment bolts).
It certainly isn't going to reduce roll unless the entire front structure of your car is in danger of collapsing, but it might let "X" amount of roll feel more composed and fool you into thinking there's less roll.
(retired structural guy)
Interesting, I was told I had to leave the strut bar in place on my convertible, so when buying a supercharger, make sure to find one that fits under a brace that is at least as stiff as the factory unit.