Download Keyframe Audio via Extrema Sampling Overlap-add (OLA) is the simplest approach to audio time stretching. Methods like the phase vocoder (PV) and waveform-similarity OLA (WSOLA) offer higher quality results but require operations like the FFT or cross-correlation. On low power embedded hardware, this cost adds up quickly. We present a content-adaptive OLA method, an order of magnitude cheaper than PV or WSOLA, whose dominant artifacts are added saturation and some spectral contrast loss. Our method reduces uniformly sampled signals to sets of timestamped local extrema, a sparse representation where the distance between points encodes the signal's information density directly into the buffer. In OLA, the crossfade duration is fixed, but no one value suits both transients and sustained sounds. We use the extrema density to inform the crossfade duration, adapting it to the signal's local content on a sample-by-sample basis. We compare our method against OLA, WSOLA, and PV using objective metrics and a listening test. Our method coherently stretches audio, preserving transients across a wide range of stretch ratios and capturing dense, layered material cleanly.