  This paper discusses how to improve the Boris pusher used to advance
relativistic charged particles in fixed electromagnetic fields. We first derive
a simpler solution to a flaw previously discovered by others. We then derive a
new analytic Boris pusher that is a minor modification to the original
split-time scheme, except for the calculation of {\gamma}. This analytic pusher
assumes that the change of {\gamma} during a particle advance is small. It is
less accurate than the pusher derived by Fei Li et. al., but is nearly twice as
fast. We will discuss when it is advantageous and when it is not.
