Problem firewall with Justified Image Grid plugin

I am using Wordfence free version with extended firewall protection enabled. I also use the plugin Justified Image Grid (JIG).

The JIG plugin uses TimThumb (an image resizing script) to show image grids on webpages (they look really great!).

The problem is that the load time of my webpages containing JIG grids are very slow, around 5 seconds. I discovered that this is caused by the Wordfence firewall. Disabling the firewall and the load times where fast (1 second).

So I want to find out which settings in Wordfence are causing the slow load times for the JIG grids.

First I found these 2 firewall rules:
rfd TimThumb <= 1.33 – Remote File Download
rce TimThumb <= 2.8.13 – Remote Code Execution

I disabled these 2 rules but that did not help.

After that I disbabled the extended protection from the firewall (so now only using the basic protection mode) and that did solve the problem. My JIG pages are now all loading around 1 second instead of around 5 seconds.

However, this does not seem to be a good solution because I had to disable the extended firewall protection.

So my question is this: is it possible to set up Wordfence with the extended firewall protection enabled but at the same time disable the issue with the slow loading JIG/Timthumb pages?

Thanks very much for the help ??

Alwin