Gun out, when not done for a while, ADS'ing while have an unusually long delay while on a server.
This delay gets increased further by whatever your ping to the server is.
The animation is not properly played, too.
This will get you killed easily in a crucial situation (i.e. suddenly running into somebody and it takes you over 1 second to raise your gun)
Example: (in this clip it takes over 1 second before my character even does anything)