Not sure about the specifications of your computer, anyway it sounds as though the issue you are facing has a lot to do with the way the Simulator is configured around the specifications of your computer. Regardless, I have faced some of these issues until I really spent some time with the simulator configuration pages, especial Under the GENERAL tab.
Here are my computer specifications, and following is the Simulator settings I am currently using. In addition, my internet speed is 450Gbps. I have also run this same configuration at 250Gbps. All my flights are in Live Mode.
OS: Windows 10 Pro
Microprocessor: Intel Core i9-10900K CPU @ 3.7GHz
Memory: 64GB memory Kingston 3200MHz
GPU: NVIDIA GeForce RTX 2080 Ti
Resolution: 4096 x 2160
Audio: I use JBL Quantum 800* Game via 2.4GHz wireless
Simulator Version: 1.13.17.0 (just released)
NOTE: My suggestion here is to go into each of these Option, place your cursor over the setting and READ the DESCRIPTION. Use your best judgement and decide ehat you Really Need and separate those from the wants to give the Computer a Chance. I still at times have to change the settings based on aircraft type, and flight. I currently am doing the Idaho North, Central, and South Bush Trips that I purchased.
OPTIONS MENU
GENERAL
GRAPHICS. (this is what I think is KEY with many performance issues)
Under PC selection (First option under SEARCH
Display Mode: FULLSCREEN
Full Screen Resolution: 4096X2160 (most likely 3840X2160 but this depends on the Display/Displays)
Global Rendering: High End
ADVANCED SETTINGS
V-Sync: ON
Frame Rate Limit: 60FPS
Render Scaling: 100
Anti-Aliasing: TAA
Terrain Level of Detail: 100
Terrain Vector Data: HIGH
Buildings: High
Trees: High
Grass and Bushes: High
Objects Level of Detail: 100
Volumetric Clouds: High
Texture Resolution:High
Anisotropic Filtering: 8X
Texture SuperSampling: 6x6
Texture Synthesis: High
Water Waves: High
Shadow Maps: 1536
Terrain Shadows: 512
Contact Shadows: High
Windshield Effects: High
Ambient Occlusion: High
Reflections: High
Light Shafts: High
Bloom: ON
Depth of Field: High
Motion Blue: High
Lens Correction: OFF
Lens Flare: ON
Glass Cockpit Refresh Rate: Medium
Flight Model
Global Preset Intermediate
Everything else is at the defaults.
NOTE: Make Sure to [F11] Apply & Save
Note: I have used Ultra Setting but found I had to change a whole lot of settings to both medium and high values, as well as low.
If I do begin to have lags or pauses, what I do is decide what is not that important in the graphics setup and has an impact on performance, then I lower those settings.
Good luck, and enjoy the flights.
BTW, I also have connected:
Logitech Yoke and Throttle system
Logitech Rudder Pedals
Logitech Radio Panel
Logitech Switch Panel
Logitech Muti Function Panel