OSR 4.1.35 is up on the nexus: http://www.nexusmods.com/oblivion/mods/23208/
This update is also available for Fallout 3 (FSR), and for New Vegas (NVSR). It is a bigger deal for FO3 as the first version to allow heap replacement there I think. NVSR has been receiving regular updates for the last few weeks, but for NVSR this is the first version to support LCSes (which don't really exist in Oblivion, so not relevant).
For Oblivion, the only big deal is that this is the first version released for Oblivion in a long time. And the first version to include source code in the same download as the dll. And the download is now organized in a manner that mod installers are more likely to handle correctly without human intervention.
But no significant performance improvements are expect for Oblivion users IIRC.
Some features were rewritten:
FPS Management
64 Hertz Fix
LCS hooks (but that has no effect on Oblivion)
hashtable profiling
Some issues with use of external heap dlls were fixed, but I don't think those were hurting any OSR users anyway (not sure that effects anyone actually, since external heap dlls still aren't working on FNV, and I doubt they work on FO3 either).
Some issues with CS profiling were fixed too, but those didn't seem to effect Oblivion.
Changed behavior of bReduceSleep (was bReduceLongSleep) and iThreadsFixedToCPUs to hopefully saner behaviors, but I think the issues they had were a bigger deal for FO3 & FNV anyway.