Although the security queues are long, they do move. If you check in on time and go straight to the queue, you shouldn't have any issues.
Check-in queues really depend on the airline you are flying with and the class you are travelling in. I've used KLM and BA on a relatively regular basis. The KLM queues are never really a problem. BA can have some horrible economy class queues, but are OK in other classes. In the absolute worst case, I think it once took me about 45 minutes to get through the BA queue, but it's usually better than that.