Civ5 runs slow and choppy

I have played roughly 500 hours of Civ5 and this problem recently started about 400 hours in and has only gotten worse and worse to the point where I have to play on strategic mode. When I do run the game normally, the first 10-20 turns run smoothly then the game gets slow and choppy for awhile until it returns to normal. This pattern repeats itself over and over again. I feel like I have done everything within my knowledge to combat this problem and have had no luck. I have factory reset my computer, basically used every possible video setting in Civ5, uninstalled and reinstalled steam and Civ5, etc... I feel as though my computer should be able to run Civ5, it is a fairly new computer from February 2014. Here are my specs:

System:
Sony
Vaio
OS - Windows 10 Home 64-bit (10.0, Build 10586)
System Model - SVF14N16CXB
BIOS - R1140DD
Processor - Intel(R) Core(TM) i7-4500U CPU @ 1.80GHz (4 CPUs), ~2.4GHz
Memory - 8192MB RAM
DirectX Version - 12

Device:
Intel(R) HD Graphics Family
DAC Type - Internal
Device Type - Full Display Device
Approx. Total Memory - 4156 MB
Current Display Mode - 1920 x 108080 (32 bit) (60Hz)

Drivers
Main Driver - igdumdim64.dll,igd10iumd64.dll1
Version - 10.18.15.4256
Driver Model - WDDM 2.0

Okay, that may be too much information, but I am stumped. Is there anything that can be done? I know in the past Sony said to hold off on Windows 10, as of early last month they Ok'd Windows 10 and I followed all the proper installation directions.

The odd thing you say is that, "it is choppy for a while, then comes good".

Is it a power setting / switching / battery issue with the laptop?

If not, I had a massive problem with Civ lagging on a i7-2620qm mobile processor. Basically, dust had built up so much that the mobile chip was throttling itself at 798Mhz to control the heat, as opposed to maximum operation. I pulled apart the laptop and redid the thermal pasting and gave it a good clean. Now it is only slightly slower loading than my i5-4460 on huge maps. And the chip, while it stills throttle every now and then, basically keeps very good uptime on the maximum clockspeed.

The way to test this (or at least the way I found it) was with a program called CPU-ID. Or maybe it was HWMonitor).If it is throttling, not only will temps be high (90 C+) constantly, you will notice the MHz are consistently low and fan speed maximum.

I'd suggest that blowing out the dust gives the most improvement and re-application of the thermal pasting was both difficult and perhaps unnecessary (but since I was in there).

Before doing ripping apart your laptop (not somethign I'd suggest unless you were confident), how does it perform in other games? Do you get lower than expected frames per second on other games?