... compiling hundreds or thousands of small files regularly. I'm trying to figure out which SSDs are fastest at that sort of workload (it's not often any of the files will be over 1Mb).
An Intel Optane 900P Series SSD (for a consumer drive at reasonable prices).
Consider all your options:
Buy more memory. 16 gigabytes / 1 megabyte = 16,000.
If you only have 16 GB (or 8GB) of memory then buying more memory would be a good investment. Reading a file, even from a harddrive, is fairly quick; it's the conversion from text to assembly language and opcodes that takes processing effort, reading the files from memory is very fast.
More memory allows more space to do the operations necessary to compile the source and allows for a larger swap file, staving off the need to fetch from storage.
It also allows more breathing room for your program to execute and to have additional necessary programs running, speaking of which, close unnecessary programs during compilation.
Any SSD will be much faster than a harddrive. You can buy an inexpensive and small SSD and be better off than using a harddrive for storage.
A 250 GB SSD will hold your operating system, a couple of games, your compiler toolchain and plenty of source code. You can use your old harddrive as a secondary drive and to backup your SSD.
Exactly which one to choose is mostly a matter of availability and price. A lot of what you are doing when writing the source code will involve very little disk activity. Once you get to the compilation that will involve reading the file, making many calculations as to how to optimize the output, and finally writing out the object file.
If you have lots of existing source code that you want to compile and intend to spend next to no time writing then the need for faster storage becomes a consideration.
It depends on what you will be spending most of your time doing, arguably a CPU upgrade might be a greater benefit than memory.
But let's assume you have gone through the above considerations and crunched the numbers, you want your question answered, as written.
- An Intel Optane SSD 900P Series (280GB, AIC PCIe x4, 3D XPoint) for approximately U$250 will provide an enormous speedup; above and beyond other SSDs.
AnandTech's conclusion is: the Optane is the fastest and most expensive, the not yet available M.2 version of the SZ985 is untested and an unknown price (expected to be comparable to an Optane and less expensive), the Samsung 970 EVO Plus Series will either save you money or gain you 4x the capacity for equal money, and the least expensive HP EX920 isn't far behind (or poor quality) and will save you U$100.