There are over 100 cores that are currently available in my repository, building 100 cores takes a very long time, mostly due to the fact that i try to highly optimize the code for the given architecture.
For example the parallel-n64 core is actually available optimized specifically for Exynos 4 (Cortex-A9), Exynos 5 (Cortex-A15.Cortex-A7), and AmLogic S805 (Cortex-A5), and in the future AmLogic S905 (Cortex-A53) and RockChip 3399 (Cortex-A72.Cortex-A53) will be added as well.
This makes it roughly 150 cores that I build each time that I updated the cores for retroarch.. I do not use automated build system as it fails on many cores that are not optimized for arm, and also due to the fact that the libretro project constantly updates their Makefiles and codes and introduce new issues and problems that I need to fix manually, also some cores take several hours to compile and link (MAME for example).
Aside from that, just building a "new core" doesn't mean it's an improvement. In fact some cores I explicitly keep using older versions from as newer cores have significant performance hits resulting in games no longer being able to play.
HOW do you figure that out? -> TESTING each core individually comparing it with it's previous version, measuring performance gain and losses in different scenarios (150 cores avg. 10min testing equals about 24hrs testing all cores in total probably closer to 30-50 hrs just TESTING)
Even if a core builds successfully doesn't mean it's working.. it can still segfault, which require code fixes, or different compiler options to get them to work... how do you figure this out? -> TESTING...
Guess who does all the work? Building? Testing? Meassure speeds between older and newer cores? Investigate in new build tools and compiler FLAGS (for example newer GCC versions).
If you guessed "meveric" you guessed correctly.
I'm doing this all by myself.
Why do I say this? To make you understand how hard it is to keep these cores as good and fast as possible, and creating updates for all cores does take several weeks, yes even months.
That is why updates do not happen that often, only two times are year or so...
I do occasionally update single cores in between if I noticed significant code changes that may benefit us.. but to be honest these happen very rarely.
Now to the two cores you mentioned for example.
"Parallel N64" is basically a dead projects. If you check the commits of the last 6 months you will see that there were mostly just commits for emscripten or android build scripts.. all stuff that do not affect ODROIDs at all, so there's no new code it's still the same... and as the project is essentially dead, I don't expect much to change here at all.
Same goes for snes9x.. the emulator is pretty much complete.. the bugfixes and changes that happen in that project you can count on one hand per year. The rest is once again build fixes for platforms as android emscripten Solaris and whatever.. nothing that helps us in any kind.
I will keep updating the cores, especially the ones that are new and are still active in development and I will keep trying to optimize them.. some of the cores I have optimized from the first version to the current version nearly doubling the speed, just by using newer tools and better compile option.. these changes are often much more important than "new code".
I''m currently focused on porting most of my work from Debian Jessie to Debian Stretch to move forward in technology as well this is a very huge task, and will include rebuilding all libretro cores as well.
When this happens I will likely updated some cores for Debian Jessie as well.. to upload new cores that are now available on the libretro project and update cores that got significant changes.
Still this is only part of the work that needs to be done.
My repository currently holds far over 2100 .deb files for Different operating systems (Debian Wheezy, Jessie, Stretch and even some that work on Ubuntu as well) for nearly all ODROIDs ever created (ODROID X,X2,U2/U3,XU3/XU4-Series,C1/C1+,C2,N1) and I keep adding or updating files every couple days: viewtopic.php?f=52&t=5908&p=220436#p220436
Once again, I'm the only one porting, compiling, testing, fixing, etc.
I can just tell you I will update it, but it might take some time, especially if you just want "updated cores" without anything specifics.. over 100 cores take time, it won't happen that often.
if you actually have an issue with one of the cores you think should/could be fixed, or see some changes on a specific core that you think that sound interesting, please let me know.. updating a single or a few cores or other programs on "request" is rather simple for me and I can do that in between, just not all at once.