The prevailing wisdom is that lower bars make you more aero and thus faster. This may be true for racers, but not necessarily true for the average cyclist. As others mentioned, higher handlebars should make it much easier for you ride in the drops, which could make you more aero. Higher bars also could make you much more comfortable on your bike, allowing you to ride more, train more frequently, ride longer distances -- thus improving your fitness.

Years ago, I had a lot of fit issues. My hands got very numb after cycling, my neck hurt and I was uncomfortable riding longer distances. I eventually figured out that my problems were all related to the handlebars being too low on my bikes. Through trial and error, I determined that I was most comfortable with the handlebars the same height as my saddle. After I made this switch, my fit problems cleared up almost immediately. My hand numbness went away, my neck quick hurting and I was able to ride much longer distances with no discomfort other than normal fatigue. I was also able to ride in the drops for as long as I wanted with no problems.

So, in my case, my cycling performance actually improved as a result of raising my handlebars. I became more fit, much more comfortable riding my bike, and was able to ride faster and for longer distances.