Most eficient way to count occurences?

I've got an array of bytes (primitive), they can have random values. I'm trying to count occurences of them in the array in the most eficient/fastest way. Currently I'm using:

HashMap<Byte, Integer> dataCount = new HashMap<>();
for (byte b : data) dataCount.put(b, dataCount.getOrDefault(b, 0) + 1);

This one-liner takes ~500ms to process a byte[] of length 24883200. Using a regular for loop takes at least 600ms.

I've been thinking of constructing a set (since they only contain one of each element) then adding it to a HashMap using Collections.frequency(), but the methods to construct a Set from primitives require several other calls, so I'm guessing it's not as fast.

What would be the fastest way to accomplish counting of occurences of each item?

I'm using Java 8 and I'd prefer to avoid using Apache Commons if possible.