first, I have to say thanks for the awesome game
I wasnt so addicted to any PC Game the last few years then I am now to factorio 
(I did play 160h the last 2 weeks 
)my game started to lag at some point (fps ~22-24 ups 44-48) and i did some research what caused that lag.
I think, its an issue with landmines, especially when they are placed near the waterside. Entity Update did take ~20-25 ms. When I did remove the Landmines near the waterside, Entity Update did go down to ~10ms and the more Mines I remove, the lower Entity Update goes (atm round about 2,5ms).
And here came a second bug. I told my construction bots to remove the minefields, but they did regularly stop working and were vanishing in the roboports. Sometimes they stop when I´m near the roboport network, sometimes they start working when I come there... I dont know what they do.
I also deactivated all mods, but it didnt change anything.
In the attached file are 3 safegames and the used mods.
The highest influence on entity update had the minefield at cu_n2, especially the mines at the right side of the outpost.
PS: I did load the savegames to check where the player is, and it didnt lag (but entity update was still very slow and varied heavily between the saves)
I hope this gets fixed, because i like blowing up the biters
So I didnt do anything else than partying and playing