Anywho, reading threw the various posts related to this framerate/client lag issue, I stumbled across something I should have thought of a long time ago. Someone stated that they had taken the higher-level graphics processing out of the hands of the EvE client and manually turned off AntiAliasing [globally] thru their graphics adapter's control interface. [One of the issues causing problems was EvE client turning on AA, or increasing the setting, without regard to client video settings]

BRILLIANT IDEA!

I'm running a Nvidia GTX-560 w/ factory overclock. Most of my global 3D settings were to let the application decide, so...
I disabled most/all of the AA processing stuff unless the tooltip said anything regarding performance was improved with this active. Those I left on, but allowed or enabled, NOT app controlled. Changed my overall setting to high-performance, then went into EvE.

I currently run 7 clients. Previously, 2 were using high LOD, Texture and Shading with the other 5 having low for these settings. AA, HDR, Shadows, and Post-Processing were disabled. No issues other than the 5 'low' clients looking like they had ships drawn by a cartoonist. With the changes to the Nvidia settings, I'm now able to run ALL 7 at Medium Shader and Texture with NO fps issues [aside from looting which is an unrelated issue]. And I think I may have some GPU left over. been playng this way for almost 4 hrs so far with numerous session changes.

If you're still having fps issues, it's something to look into.