  The investigation of samples with a spatial resolution in the nanometer range
relies on the precise and stable positioning of the sample. Due to inherent
mechanical instabilities of typical sample stages in optical microscopes, it is
usually required to control and/or monitor the sample position during the
acquisition. The tracking of sparsely distributed fiducial markers at high
speed allows stabilizing the sample position at millisecond time scales. For
this purpose, we present a scalable fitting algorithm with significantly
improved performance for two-dimensional Gaussian fits as compared to Gpufit.
