Security or performance issue of setting a high timeout for the Elastic Load Balancer?

I noticed an error today for one of our long running scripts. A 504 gateway error. I eventually tracked down the issue to being the ELB timing out after 60 seconds whilst our script needs around 5 minutes to perform it's job.

After increasing the ELB timout to 5 minutes using the AWS console, everything worked perfectly. However, I am now wondering if there are any performance or security issues with this global setting?

I don't have expertise in this field.