Yes, but only a small amount. Almost all brushless ESCs use microprocessors, and these require a certain amount of time (called latency) to react to the incoming sensor signals and step the motor drive to the next commutation pattern. This time delay retards the timing. The higher the free-running RPM, the farther the timing is retarded.

If you're running VTA or 17.5 1s 1/12 scale, the timing isn't affected much at all. If you are running an 8.5T on 2s, then it will be much more noticeable.