How to fix lagging issues with the ShooterGame demo in 4.4.3?

I remember Shooter Demo worked really very smooth on Unreal engine 4.2 but in The version Unreal Engine 4.4.3 there are so many lags especially while shooting. The fps of the games becomes too low so how can I fix it?

Here are my system specs - Operating System
Windows 8.1 Enterprise 64-bit
AMD A4/A6/A8/A10 118 °C
Richland 32nm Technology
7.00GB Single-Channel DDR3 @ 798MHz (11-11-12-28)
LENOVO Lenovo G505s (Socket FT1)
Generic PnP Monitor (1366x768@60Hz)
768MB ATI AMD Radeon HD 8550G + HD 8500M Dual Graphics (Lenovo) 65 °C
2048MB ATI AMD Radeon HD 8500M Series (Lenovo) 67 °C
CrossFire Disabled
931GB Seagate ST1000LM024 HN-M101MBB (SATA) 43 °C
Optical Drives
Conexant SmartAudio HD

Hi Vikhyat Singh,

Are you still experiencing this lag in 4.5.1?

Hi Wikhyat Singh,

We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will offer further assistance.
Thank you.