You may run into lag because of sending too many requests to the server in 1 minute. This is because of wordfence throttling those that send too many requests. The reason this is done is to sieve out negative crawlers which steal our chapters and possible hackers as well as lighten the load on the server. I apologize for any inconvenience caused, but it should get better over time as I fine tune the settings.
p.s. the current request limit per minute is 60.