The m4's 4K performance has been rather weak throughout our review and that's no different in Atto Disk Benchmark. The m4 was slower than the RealSSD C300 every step of the way, often dramatically so. Even when compared to the 120GB 510 Series drive, the larger 256GB m4 was considerably slower when working with 8K, 32K and 128K sample data.
While Crucial's latest drive demonstrated subpar read performance, we find the complete opposite when measuring write performance with Atto Disk Benchmark. The m4 had a stellar showing, ousting the RealSSD C300, SSD 510 Series, and even the Vertex 3 when looking at 1K and 2K performance, while the 8K, 32K and 128K performance was also very strong.