From a quick look it seems like you're doing gl.createBuffer() in a loop each time you're drawing, and never call gl.deleteBuffer(). It seems like WebGL will call deleteBuffer() automatically when the object is garbage collected by the JS runtime, but calling it explicitly when you're done with it will probably fix this particular issue.
Also a suggestion, try to allocate your buffers only once on setup, and reuse them each time you're drawing. Just call gl.bufferData() in case you need to push new data. Don't use gl.bufferSubData() unless you come up with a clever way to avoid pipeline stalls such as maybe a rotating queue of buffers. This approach might or might not improve performance, but I see little reason not to do it.
To make this work you prbably have to create a vertex arrays object explicitly using gl.createVertexArray(). This object is used to capture the vertex attrib pointers. Call gl.bindVertexArray() before gl.enableVertexArray() and gl.vertexAttribPointer(). Later, in a simple draw you need then only call gl.useProgram() and gl.bindVertexArray(), but there is no need to bind buffers or set vertex attrib pointers.
