I was informed a little while ago of a JIRA issue that has consequences for those Scripters who - firstly - make scripts for attachments, or vehicles, or regularly rezzed items, which is quite a few of us, and - secondly - compile things with "Mono", which is also a popular pastime.
I made a note of this in my TwitterThing and, in recent days, have seen at least three separate references to the problem, despite the issue first being raised in SVC-3895 in February of this year (so, a very young JIRA issue, then).
Of course, on the TwitterThing one is restricted as to the length of explanation, and on that basis I would like to make brief mention here. My analysis is the following:
The initial JIRA issue and subsequent comments indicate that rezzing Mono scripted objects is murderous to the FPS and performance of a region.
"Rezzing" in this instance is not only rezzing objects via script - which would mean bullets - but also, vehicles and attachments entering the region.
Mono scripts still have the usual advantages regarding efficiency and such after they are rezzed. (They do I am told use more memory which might be significant if script limits are enacted - but that is a different issue.)
Therefore: for anything which might regularly be rezzed, most significantly bullets but also attachments and vehicles, which are re-rezzed on teleport or region crossing, I would advise recompiling in LSL to avoid the apparently noticeable performance impact. (I have not tested this myself beyond the odd unrepresentative experiment, but many scripters in the comments of the JIRA whom I personally trust and respect have done so.) For static devices, sales boxes, vendors, servers of all flavours, I would advise using Mono.
On a separate note, it is perhaps an indication of how long it has been since I properly wandered the Grid that I am shocked at the current state of Region Crossing. It really is like participating in some sort of novelty fairground attraction, where one is attached to a long piece of stretchy substance, flies off into the distance (without being able to control the process) and then is rapidly thrown backwards. This sort of thing might be amusing to the Young but really does not divert me, and I cannot help but question the Laboratory's decision in implementing it now.
Oh - and somebody erected a gallows next to my small Library plot in Zindra, which in another world might be taken as a threat, but here, is more of a welcome sign.