Reinstalled BS3 this week and I noticed the Vikhr missle induced frame-rate drop. Did Flappie's track-file and only noticed 1-5 FPS drop. However, when shooting over land at targets, the FPS would go from 58 frames down to 18 frames. Randomly, just once, I was able to get 72 FPS while hovering and 68 FPS firing a Vikhr missile.
Attached is the options.lua and dcs.log from Flappie's track-file and I've also provided a log and track-file of my land based test.
options.lua
01_Vikhr_Test_Spanueh_dcs.log
dcs.log
01_Vikhr_Test_Spanueh.trk