The lower your ttl, the higher the traffic on your dns server. The more the load on the internet in general as other dns servers will have to query your server

The lower your ttl, the higher the traffic on your dns server. The more the load on the internet in general as other dns servers will have to query your server more often which might be slower because of the extra traffic. There are reasons for low ttls... like your information changes quite often. I've managed tons of domains where the dns was basically setup and then never really changed. If it was going to change, we knew well in advance so we could do 48+ hours for a ttl. If you need a low ttl do it, if you don't, be a "good citizen" and use a higher one.