OFFSET and LIMIT performance issue

[Rick James]

Guess what?
LIMIT 5 OFFSET 200
has to walk over 200 rows before getting the 5 you want. Performance gets slower and slower.

A much better way is to use a UNIQUE key (possibly the PRIMARY KEY), and...
First time:
SELECT ... ORDER BY key LIMIT 5
Remember the last `key` fetched as $left_off
Next time, do
SELECT ... WHERE key > $left_off ORDER BY key LIMIT 5
Again, remember the last `key` fetched.

If you don't have a UNIQUE key, maybe you should add one for this purpose. Performance stays Order(1).