I see two distinct issues:
set_time_limit:
Most webservers have a restriction on the time a php-script may execute, that's to protest the server. If you are working with a lot of feeds and/or large feeds you will reach the limit. On some servers it is allowed to extend
the limit using set_time_limit, on yours it is not.
high load:
The feed import might take a lot of resources, as a basic protection the script will check the system load. By default it is set to 10, for must server a system load of 10 is pretty high, however on other servers, with a lot of CPU's a higher limit might be acceptable. However you wouldn't be the first one with a disabled website by the hosting.
If you are running the import from the administrator tab the import will simply stop if the load is to high, if you are running the feedcron.php directly the script will wait untill the load drops ( or the time limit is reached)
From what I see you are not reaching the time limit, but the script simply stops because of the high load. (and you probable didn't notice the warning before)
You can override the default settings in your feeds.php see :
affiliatefeeds.nl/en/217-load-protection.html
