Hi, will create tunnels between sites.

Just want to learn, which of above protocols use less resources (cpu) on router, there will be about 40 tunnels.

I think that they are the same as far as resources go, especially if you don't use IPSEC with L2TP. I always suggest people to go with L2TP if possible. It uses UDP transport. If urge you do to a google search regarding the disadvantages of running tcp traffic inside a tcp tunnel.

GL

i agree, l2tp is best. . . however, since its udp it will severely be impacted by packets being out of order - encryption gets out of sync and everything comes to a halt.

They both do have some similarities as far as resources concerned though there are few important difference between pptp and l2tp. This difference are key to configure any of these protocols to any device. I have rgone through to the comparison of pptp and l2tp and learn exactly How to Configure PPTP or L2TP VPN on Operating systems with step by step analysis. This detailed review includes more than 16 steps supported by images.

L2tp can use mppe too.

Maybe also look into SSTP, more secure than PPTP, if site 2 site tunnels are between Mikrotiks, you don't need certs