ISP and "packet paths":
When you game (or actually do anything) on a network - which includes the internet, your actions and the responses to those actions are bundled into data packets, addressed, and sent back an forth.
Packets are of a fixed size and the data (say a video for example) is broken into many packets and sent to the destination IP address. The packets may take different routes and are simple reassembled when and as they arrive at the destination IP address
So if some of the packets get "lost" they be need to be resent. Or packets may get delayed along the way due to heavy traffic (just like a traffic jam) and/or some delays imposed by ISP's, cheaters (common in gaming), blocked routes, etc. Any number of reasons.
However, many home routers also allow the network administrator to prioritize traffic, block sites, impose restrictions via "parental controls". May or may not be some setting in your router slowing things down.
Or just a buggy router.
There are two "tools" that you as an end user can run from the command prompt on your computer to help find and identify bottlenecks slowing your "packets" incoming or outgoing.
The tools are "tracert" and "pathping". Both tools are limited and not a sure bet to find any given problem per se. They should however, provide some insight as to where the problem is occurring.
Start learning via the following link:
https://www.lifewire.com/what-are-hops-hop-counts-2625905
Then google for additional links and information as you feel necessary.
There are other tools. E.g.:
http://techgenix.com/top-11-networking-commands/
Focus on tracert and pathping. See what you can find and learn.
Do not immediately react and start changing your system. The key is to be very certain about the source of the problem and, hopefully, the fix to be applied.