An imaging device may have an array of image sensor pixels arranged in rows and columns and column readout circuitry coupled to the array. The rows of pixels may receive drive signals from row driver circuitry, and the drive signals may be sent from timing circuitry based on the locations of rows within the array. In particular, rows closer to the readout circuitry may require less settling time and therefore be driven faster than the rows further from the readout circuitry. All of the rows may be driven in a single direction, or the array of pixels may have a cut, in which case rows above the cut may be driven up and rows below the cut may be driven down. A frame buffer may be used to store the signals generated by the rows of pixels and may account for the asynchronous read out of image data.