I have set up, by the book from the MT manual a site to site PPTP client server connection.
In the homeoffice I hava 4/1Mbps ISP link cable, and in branchoffice a 2Mbps/256Kbps link adsl.
I have tried with or withou commpression in the profile for the user, without change tcp mss and without encryption, but I still have a slow response when I try to download a file via pptp link, I have like 20-30 kbytes/second, I should have more, because no one is using upload in the homeoffice.
Any advice to create an alternative site to site, or guides to optimize a PPTP link.

Thanks in advance.

20-25kbytes/sec is about right since your lowest link speed is 256kbits/sec (2m/256k).