It should not escape your notice
"You should not fail to understand this" or "Do not ignore this"
that one day with the Lord is like a thousand years
"that from the Lord's point of view, one day is like a thousand years"
The Lord does not move slowly concerning his promises
"The Lord does not move slowly to fulfill his promises"
as some consider slowness to be
Some people think that the Lord is slow to fulfill his promises because their perspective of time is different than God's.