Skyrim SE compressed BSA format support
In 0.46.0 the native support for BSA version 103 and 104 was added (see issue #5000 (closed)). SSE introduces a revision of the format, version 105, which makes use of LZ4 compression format that is over 10x faster to decompress compared to zlib-compressed archives in older games at the cost of the file size, which would still be significantly smaller than the size of a file in an equivalent Morrowind BSA. This is beneficial to asset creators which are interested in the game's superior performance, as it lessens much of the CPU overhead in file loading.
Although the number of this issue isn't quite as cool, it should be possible to add the support of that format to OpenMW easily.