Hi,
The shader compile/link operations are carried out asynchronously to your Javascript in a separate GPU thread./process (even without parallel compile implemented), so those calls appear to complete quickly. (for Chrome at least).
However when you make any WebGL call that needs to see the result of the compile/link operations, that call waits for them to complete. For obvious reasons, getProgramLogInfo() is one of those calls, and hence the delay you see is not the time taken to get the log, but is mostly the time waiting for the compile/link to complete. The same applies to the getProgramParameter() call, eg getting gl.LINK_STATUS