By ByteBot
Microsoft shipped C# Dev Kit 11.0 as a pre-release this week, and the performance numbers make the previous version look like a liability. The VS Code extension — which was running six separate managed processes at startup — now compiles to a single Native AOT binary. The result: solution loads that are up to 180x faster, memory consumption cut by 85%, and incremental build times down to under a second.
Six Processes to One
The old architecture had a straightforward problem. Every time you opened a C# project in VS Code, the Dev Kit launched six managed processes — each going through antivirus checks, loading images from disk, and running JIT compilation before a single line of IntelliSense appeared. On a large solution, that added up. The 407-project Aspire solution took 84.1 seconds to load.
Version 11.0 consolidates those six processes into a single CSDevKit native executable, compiled ahead-of-time using .NET Native AOT. There is no runtime to load. There is no JIT on the startup path. The Aspire solution now loads its active file in 0.47 seconds.
Microsoft also changed the loading order: the active file loads first, so you can start editing immediately while the rest of the workspace loads in the background. Load time is now constant regardless of project count.
The Numbers
Load times by solution:
- Aspire (407 projects): Active file in 0.47s (was 84.1s) — 180x faster. Full solution in 3.0s — 28x faster.
- Orleans (155 projects): Active file in 0.53s (was 50.3s) — 95x faster. Full solution in 2.3s — 22x faster.
Build times:
- No-change build: 0.88s (was 34.4s) — 39x faster
- Single file changed: 2.1s (was 36.1s) — 17x faster
Memory usage:
- Aspire: 316 MB (was 2,072 MB) — 85% less
- Orleans: 208 MB (was 1,307 MB) — 84% less
One developer on daily.dev captured the sentiment well: “180x faster load time? ok, that’s not an update, that’s an apology.” Harsh — but these are not incremental improvements. The old architecture was a known bottleneck that finally got addressed.
Project Caches You Can Commit
There is one feature in 11.0 that deserves more attention: committable project caches. The first time you open a solution, Dev Kit builds a project cache. On subsequent opens, it uses that cache directly. You can commit those caches to version control — meaning fresh clones and CI environments get instant tooling on first open, with no rebuild required.
For teams running Native AOT-aware CI pipelines that spin up fresh environments on each run, this removes the “waiting for C# tooling to initialize” tax entirely.
Also Shipping: MSBuild IntelliSense and C# Doctor
Beyond architecture, 11.0 adds full language support for .csproj, .props, and .targets files — completions, diagnostics, go-to-definition, quick fixes, and package vulnerability warnings via CodeLens. This has been a long-requested feature for developers who modify build files regularly.
The C# Doctor is a new centralized health-check tool that diagnoses environmental issues: missing SDKs, unavailable runtimes, failed package restores, and vulnerable dependencies. Instead of cryptic errors scattered across output panels, there is now one consolidated view of what is broken and why.
How to Get It
C# Dev Kit 11.0 is available now as a pre-release. Open VS Code, go to the Extensions view, find the C# Dev Kit extension on the VS Code Marketplace, and select Switch to Pre-Release Version. The version jump from 3.3 to 11.0 is intentional — Microsoft is aligning Dev Kit’s version number with the current .NET release cycle going forward.
Microsoft notes this is the first in a planned series of posts on the new architecture. More implementation details on the Native AOT migration are coming.
