for (int i = 0; i < 1000; i++){ double st_tmp = CFAbsoluteTimeGetCurrent(); retBuffer = [self.enhancer enhance:pixelBuffer error:&error]; double et_tmp = CFAbsoluteTimeGetCurrent(); NSLog(@"[enhance once] %f ms ", (et_tmp - st_tmp) * 1000); } When I run a CoreML model using the above code, I notice that the runtime gradually decreases at the beginning. output： [enhance once] 14.965057 ms [enhance once] 12.727022 ms [enhance once] 12.818098 ms [enhance once] 11.829972 ms [enhance once] 11.461020 ms [enhance once] 10.949016 ms [enhance once] 10.712981 ms [enhance once] 10.367990 ms [enhance once] 10.077000 ms [enhance once] 9.699941 ms [enhance once] 9.370089 ms [enhance once] 8.634090 ms [enhance once] 7.659078 ms [enhance once] 7.061005 ms [enhance once] 6.729007 ms [enhance once] 6.603003 ms [enhance once] 6.427050 ms [enhance once] 6.376028 ms [enhance once] 6.509066 ms [enhance once] 6.452084 ms [enhance once] 6.549001 ms [enhance once] 6.616950 ms [enhance once] 6.471038 ms [enhance once] 6.462932 ms [enhance once] 6.443977 ms [enhance once] 6.683946 ms [enhance once] 6.538987 ms [enhance once] 6.628990 ms ... In most deep learning inference frameworks, there is usually a warmup process, but typically, only the first inference is slower. Why does CoreML have a decreasing runtime at the beginning? Is there a way to make only the first inference time longer, while keeping the rest consistent? I use the CoreML model in the (void)display_pixels:(IJKOverlay *)overlay function.