I reinstalled the following on all the PCs and laptops (including my wife's Sager).

STALKER: Shadow of Chernobyl + Starter Pack mod (ZRP, HD characters)
STALKER: Clear Sky + Atmosfear 3 + STCS weapons mod
STALKER: Call of Pripyat + Atmosfear 3 + Absolute Nature 4.04 + STCoP weapons mod
plus
STALKER Anomaly + Boomsticks & Sharpsticks mod pack.

I've been playing Clear Sky all evening. Ugh. Clear Sky can still knock the frame rates down.