1 Terminology
First of all, we agree on terms with the same meaning. There are basically three ways in which the performance of LOTUS can be bad.
- Poor frame rate or strong frame fluctuations:
- anything consistently below 25 FPS can be considered a bad frame rate
- Frame fluctuations mean that the frame rate fluctuates constantly and significantly between values over a long period of time. Fluctuations of up to 15 FPS are quite normal, everything beyond that needs closer examination
- Micro stuttering
- are very short, frequent, constant standstills of the simulator in the millisecond range
- These are usually only visible while driving through a not quite cleanly fluid image.
- Example: [MEDIA:https://youtu.be/4XZ_QAXR--U]
- Stuttering or reloading lagsfreeze the simulator again and again for a considerable, noticeable time - example:
-
[MEDIA:https://youtu.be/vd2N2LImncY]
2 General test conditions
For a meaningful test, a starting situation should first be defined. Starting from this, a single, unique parameter is always changed and the effect on the performance of the game is looked at.
A good starting situation should be representative for a typical game scenario, therefore typical background programs should run in the starting situation.
However, a precondition for any test is to keep Windows itself, the graphics and sound drivers up to date!
The computer running LOTUS should also meet the minimum requirements - or of course be better than these. 
By the way, the framerate can be easily displayed using the Steam-Overlay.
Further information can be found in the LOTUS performance window. It opens with the key combination Ctrl+Shift+Alt+W. The Display On/Off button starts the measurement process. For maximum information value, the bar should be left full in a representative situation (e.g. after jerking or frame collapse) until the end and then the measurement should be stopped by pressing "Display On/Off" again and, if necessary, screenshotted.
Disclaimer: This manual was written at a time when LOTUS knew neither weather nor traffic. If this is the case later, the manual must be extended!
3 Test - Initial game scenario
The game scenario should always be retained in the first part of the test and represent a reproducible game situation. This situation should always be
- the same map and the same vehicle
- at the same entry point
- at the same time on the same date
The Quickstart button can speed up the reload, but changes the time depending on the local time, so for test situations loaded with Quickstart care should be taken not to let too much time pass between tests and no relevant changes, like from day to night.
In addition, the scenario must be tested in three different variants to be able to make statements about the causes of the performance problems:
- Load the map with the vehicle, drive off immediately and measure the performance during this lap
- Load the map with the vehicle, drive one lap and then, in a second lap, measure the performance
- Load map with vehicle, drive one lap and then measure the performance while stationary
Due to the "laps" mentioned above, the chosen map should allow for small laps. The "Diorama" map included in the standard content does not necessarily make it too easy for a computer, so that the performance tests are meaningful, and allows small driving laps, in order to make measurements again at the starting point afterwards.
4 Test - Computer performance
4.1 Closing programs
For a meaningful test, performance-intensive programs should be closed, such as Chrome, Spotify, Skype, Discord, Photoshop, Fraps, DXTory or torrent programs. After the test they may be switched on again 
---> After closing these programs, the selected game scenario should be started and tested.
4.2 Outsourcing LOTUS
As a next test, it is recommended to install LOTUS at another location as a test if the computer has several hard disks. In general, LOTUS should not be installed on USB drives of any kind!
For this test
- LOTUS can be installed on the hard disk that does not contain the Windows installation, but not on a USB drive
- the Windows page file(s) should not be set on the hard disk where LOTUS is located.
To install LOTUS in a second Steam library in a different location, change the following settings:
Steam Client >> Settings >> Downloads >> Steam Library Folder >> Add Directory
To change the Windows swap file(s), the computer must be restarted. For the setting (example: Windows 7):
Right click on My Computer >> Properties >> Advanced System Settings >> Advanced >> Performance - Settings >> Advanced >> Virtual Memory - Change
It is recommended to provide at least as much virtual memory as you have real memory. In my example, I set it to three times that amount, but for performance reasons, the swap file and LOTUS are on the same hard disk, which is not the Windows drive.
4.3 Reading performance data
To give us an overview of the performance of your computer, you can download CPU-Z to better describe the individual hardware components. Data that we are interested in
- Operating system and architecture (32/64bit)
- Processor clock frequency
- Number of processor cores
- Working memory
- Type of hard disk (HDD/SSD/...)
- Setup type (Desktop/Laptop/...)
- Graphics card designation
- Graphics memory
- Graphics chip clock frequency
- OpenGL version (can be found in the LOTUS logfile)
5 Test - Graphic settings
First, please set the VSync graphics option to OFF and the frame rate capping to 1000 or more to not affect the test results.
The graphics options in LOTUS have a Preset slider that combines well-matched settings. We will now use this slider to change the graphics settings, so you may want to make a note of them (or save them later). You can use the function that exports the options to a readable text file, which saves you some work. Keep this file in a separate place so that it is not overwritten by another export...
First, set the Presets slider to the highest possible value that your computer can handle without permanently having less than 25 FPS in the original game scenario.
---> Measure again the performance, framerate and lags!
Next, lower the graphics slider one level.
---> Measure again the performance, framerate and lags!
If you have achieved a significant improvement in performance, it is now necessary to activate and test one after the other (!) the options in which the well-functioning preset differs from the poorly functioning one. To do this, you have to set one option after the other to the higher value of the previous level, restart LOTUS, load your initial situation and test. Once you have found the option that causes your problems, you can leave it out for the time being and then add more options.
Last but not least, and if everything did not work, you should repeat the same procedure with your graphics driver settings. Lower the options one by one and test if one of them is responsible for the bad performance of LOTUS.
Hot candidates for improvements are anisotropic filtering, antialiasing settings, triple buffering, anisotropic sampling optimization, trilinerary optimization, etc. When in doubt, try these settings and restart LOTUS again and again to test the performance.
6 Test - Content
If you've reached the lowest graphic settings and still haven't been able to make any improvements, let's take a look at how LOTUS responds to the smallest possible tasks. Install the attached map "Test Ei" and the attached vehicle "Test bahn" by putting both files into your addons folder and restarting LOTUS.
---> Load this map and the vehicle and judge the performance.
7 Report to the developers
Once down here, there are two possibilities. Either you want to report that the performance is bad even in the minimal case, or that turning off option XY on your computer will do wonders for the performance.
In both cases we need a detailed description of the initial situation:
- What kind of system do you play on? See hardware details a bit further above.
- Which graphic settings do you use? You can give us the text file of your option output or - better - use a standard graphics setting and tell us which one.
- On which card with which vehicle did you test?
- What date and time did you set for the test?
- Which activity caused the problems?
- Driving after loading
- Driving after an already completed lap
- Standing after an already completed round
Finally, we are interested in a performance measurement window that was recorded while the problems occurred and, if applicable, a description of how you were able to fix the problem.
