Battle of Stalingrad slight pause when aircraft merge

Public IL-2 Battle of X (BoX greatest battles series)
1

Noticed this in Battle of Stalingrad, it doesn’t happen in Rise of Flight

The initial merge of aircraft causes a huge frame drop then its ok

In rise of flight the merge is smooth and the enemy aircraft flies past smoothly.

Any of you computer whizzes know how I can remedy this.

System

Phenom Quad Core

8gig DDR3

Geforce 660Ti 3 gig

game running from an SSD ahci enabled

advice would be appreciated

2

sorry can’t help.
got some minor graphic issues but i don’t have this problem… (or at least haven’t noticed it…)