[syslog-ng] Coming from Graylog to Syslog-NG

Dear, I've implemented Graylog to receive around 5000-6000 logs/sec, but I have several problems: INPUT greater than OUTPUT so the journal increase a lot and the system crash, mainly. Now I want to use Syslog-NG, because I used it in the past but for 100-200 logs/sec. Here is my questions: 1) If I use Syslog-NG with a flat text file to receive 5000-6000 logs/sec, using s fast disk from my storage, do you recommneded to me this option ??? 2) As an extra benefit, what is the best and simple way to have a graphical view of all the logs ??? Thanks a lot, and maybe I'll ask you again about this topic in accordance with your comments. Roberto