Here is what I have found out so far.

There is capping / throttling. This is done by area / exchange. Some sort of limiter device has been installed which is doing auto-capping.

When a certain limit for bandwidth usage is reached for that area / exchange, the limiter kicks in and throttles down the connection.  Until the bandwidth usage drops below the set limit.

The lower / minimum limit is based on your package. Meaning, if you are on a 1M package, you may be throttled down to 30KB/s (example only). If on a 4M package, it will go down to 100KB/s (example only). I think we users can easily test this and get the correct approx figures if we want.

This is being done for international downloads. Local downloads are not affected. My tests also indicate this. As in a previous post of mine, you can use this link to see what speed you get. This should be the international download speed unlike the normal TM speedometer which is local speed.

http://download.tm.net.my/index.php

Please try it and report your package and speed.  I get:
1 Mbps package = 0.27 Mbps.