The May 2026 MSVC preview, targeting the v14.52 toolset, adds C++23 consteval propagation (P2564R3), which allows consteval calls to propagate through non-consteval contexts where the result is provably constant. C++ modules receive reliability fixes addressing edge cases that caused incorrect symbol resolution. On ARM64, the compiler now generates improved Neon vector loads, better loop unrolling heuristics, and correct indirect tail calls. For x64, popcount intrinsics and bitwise operations benefit from additional peephole optimizations. The vectorizer gains enhanced SLP PHI node support and a fix for an AVX2 reduction loop miscompilation that could produce wrong results silently. AddressSanitizer ships heap address caching, reducing allocator overhead in heavily instrumented builds. A notable correctness fix rejects reinterpret_cast of function pointers in constexpr contexts that were previously accepted but undefined — existing code relying on this pattern will need adjustment, making this the one item to review before adopting the preview. The release resolves more than 26 community-reported tickets.