Forgot to post the performance numbers and error that happens. Also, I found it interesting that the first read of a 512 byte block is relatively fast, while opening the same file again and reading the same 512 bytes a 2nd and 3rd time is very slow. Maybe just some timing thing, but seems to happen every time.
Running tests without audio running
Write 32 MB, 512 chunk: Passed: 75688028 us, 443325 bytes/s
Read 512, 512 chunk: Passed: 396 us, 1290517 bytes/s
Read 512, 512 chunk: Passed: 2294 us, 223144 bytes/s
Read 512, 512 chunk: Passed: 2294 us, 223173 bytes/s
Read 32 MB, 512 chunk: Passed: 21002816 us, 1597615 bytes/s
Read 32 MB, 1K chunk: Passed: 17008792 us, 1972769 bytes/s
Read 32 MB, 2K chunk: Passed: 10975566 us, 3057193 bytes/s
Read 32 MB, 4K chunk: Passed: 8016941 us, 4185440 bytes/s
Read 32 MB, 8K chunk: Passed: 6638796 us, 5054294 bytes/s
Read 32 MB, 16K chunk: Passed: 5884563 us, 5702110 bytes/s
Read 32 MB, 32K chunk: Passed: 5884699 us, 5701978 bytes/s
Running tests with audio running
Read 512, 512 chunk: Passed: 397 us, 1286723 bytes/s
Read 512, 512 chunk: Passed: 2296 us, 222987 bytes/s
Read 512, 512 chunk: Passed: 2297 us, 222823 bytes/s
Read 32 MB, 512 chunk: f_read error: 1, bytes read = 0, loop 6
Read 32 MB, 512 chunk: Failed