title: SDL2 - RenderPresent taking 20-30+ms randomly (in a Node.JS FFI call)
body: <p>I've been updating a Node.JS FFI to SDL to use SDL2. (<a href="https://github.com/Freezerburn/node-sdl/tree/sdl2" rel="nofollow">https://github.com/Freezerburn/node-sdl/tree/sdl2</a>) And so far, it's been going well and I can successfully render 1600+ colored textures without too much issue. However, I just started running into an issue that I cannot seem to figure out, and does not seem to have anything to do with the FFI, GC, speed of Javascript, etc.</p>
  
  <p>The problem is that when I call SDL_RenderPresent with VSYNC enabled, occasionally, every few seconds, this call will take 20-30 or more milliseconds to complete. And it looks like this is happening 2-3 times in a row. This causes a very brief, but noticeable, visual hitch in whatever is moving on the screen. The rest of the time, this call will take the normal amount of time to display whatever was drawn to the screen at the correct time to be synced up with the screen, and everything looks very smooth.</p>
  
  <p>You can see this in action if you clone the repository mentioned above. Build it with node-gyp, then just run test.js. (I can embed the test code into StackOverflow, but I figured it would be easier to just have the full example on GitHub) Requires SDL2, SDL2_ttf, SDL2_image to be in /Library/Frameworks. (this is still in development, so there's nothing fancy put together for finding SDL2 automatically, or having the required code in the repository, or pulled from somewhere, etc.)</p>
  
  <p>EDIT: This should likely go under the gamedev StackExchange site. Don't know if it can be moved/link or not.</p>