Slow installation

Please, can you help me, why this is sooooo slow?

Proceed with this action? [y/N]: y
[CryptoC] [1/5] Fetching boost-all-1.65.1.txz: 100%    924 B   0.9kB/s    00:01
[CryptoC] [2/5] Fetching boost-libs-1.65.1.txz:  51%    5 MiB 204.8kB/s    00:41 ETA^[[B
[CryptoC] [2/5] Fetching boost-libs-1.65.1.txz: 100%   10 MiB  97.7kB/s    01:51
[CryptoC] [3/5] Fetching icu-59.1,1.txz: 100%    9 MiB  88.3kB/s    01:47
[CryptoC] [4/5] Fetching boost-jam-1.65.1.txz: 100%   94 KiB  96.5kB/s    00:01
[CryptoC] [5/5] Fetching boost-docs-1.65.1.txz:  47%   16 MiB  57.3kB/s    04:34 ETA

I mean ...100kB/s on a 350Mbit fiber feels quite odd... :/ I disabled IPv6. This is in a jail
I can't help you with your speed issues but I do want to ask ...

Is the very pissed-off looking cat in your profile pic, your cat?
Heh, thanks :) Actually I found the cat pic roaming the internet a loooong time ago and I wish it were mine...
Are you using PF or IPFW to filter traffic to/from the jails? How have you configured the networking between the jails and the outside world?