Running CS1.6 with Source

[711player]

Since the last major update (hatless), we've been having trouble running our 1.6 servers on the same box as a source server. I thought it might be our host, but I can duplicate the problem on my computer. Whenever a source server is running, it increases the CPU usage of the 1.6 servers. Here's some screen shots of what I'm talking about:

(YELLOW) Running a 1.6 mod w/bots - metamod/amxx
(PURPLE) Running a default tf source - NO metamod/sourcemod
http://player.711clan.net/images/for_forum/aowc/rb_and_tf2.jpg

Same setup but killing the source server (arrow)
http://player.711clan.net/images/for_forum/aowc/rb_and_w_tf2killed.jpg

So nobody thinks I'm crazy, heres a cpu usage history of a default 1.6 (YELLOW) no mods and a default tf no mods (PURPLE), also with the source process being killed:
http://player.711clan.net/images/for_forum/aowc/defcs_and_deftf2_killed.jpg

In case anyones wondering, or thinking that the cpu usage average is misrepresented, this shows three default 1.6 w/no mods running together:
http://player.711clan.net/images/for_forum/aowc/three_cs16.jpg


Something is clearly not right. Why are the 1.6 servers being affected so when a source server is started? Has anyone else noticed this? What can we do to resolve it?

Edit: specified hatless

[joe.powell]

Its a known issue with running hlds.exe and srcds.exe on the same core, or even the same machine, its in loads of guides about it failing performance