I have no experience with the RV-3 series, but I have owned a RV-6 in the past. The aileron forces were very light at slow speed and got heavier and heavier with speed increase, specially above 140-150 KIAS. In my opinion, that was great!
The trailing edge radius and skin shape has great effect on aileron forces as others have mentioned and may be the cause and solution of your problem.
From flight testing another aircraft, with totally different control system, but very similar aileron shape, I learned that rigging both ailerons with leading edge down (trailing edge up) exposes the aileron “nose” to the airflow and reduces the forces considerably, increasing the aerodynamic balance effect.
Although playing with the rigging may help with your issue, I DO NOT recommend that path. You may get in to trouble if you do it too much and I have seen ailerons going to full deflection by themselves requiring force to bring the stick back to neutral. How much is too much? Only testing and/or aerodynamic simulation will tell you, so be careful!
My recommendation would be to check if your ailerons are properly rigged (trailing edge down will increase forces and up will reduce forces) and if the hinge is at the correct position. Hinge forward of the correct position or ailerons a little bit high will increase forces considerably.
Good luck and when you find the issue, remember to post the findings here.
Fabricio