It is difficult to explain the issues Sins have without going into too much "tech" which some will not understand. The problem is that Sins is a 32 bit game. With a two gigabyte memory limit. This is nothing new. Since all 32 bit games have a 2 gig memory limit. However Sins is NOT like other 32 bit games. Most games load their assets "on the fly", or only as needed. Some games unload what is not needed. Sins on the other hand loads almost ALL of its assets at game startup. These assets remain loaded throughout the entire game. The size of the map, and the amount of players, or AI's also determine how much ram will be used.
In 2006 when Sins was first conceived 2 gigs was considered to be "plenty" of memory. So most game developers didn't have to worry about hitting that dreaded 2 gig brick wall. As time went on Computers, and Sins itself evolved into their present state which is Diplomacy, and dual/quad core 64 bit systems. Things have changed over the years. Much more content was added to Sins with the two expansions. Most people now use 64 bit systems, and have much more than 2 gigs of ram. However Sins still remains a 32 bit game. With a two gigabyte hard coded memory limit. Sins WILL CRASH when the game reaches that 2 gig limit.
There is some misunderstanding about the 2 gig crash issue. The dump happens when Sins reaches 2 gigs of Ram Usage. That means the ram Sins itself uses. NOT what your entire operating system, and/or other programs you are running combined uses. Only the ram that Sins uses. No matter how powerful your system is. If it is 32, or 64 bit, or if it is Windows XP, Vista, or Windows 7. Sins WILL CRASH when it hits its 2 gig ram limit. It is hard coded into the game.
Nobody was aware that this would be a major problem back when the game was first designed, because Sins was designed based on the hardware standards of 2006-2007. Before 64 bit OS's, Quad Core cpu's, and 4+ gig ram systems became the standard that they are now. There is nothing that can be done about it. Except to re-write Sins in 64 bit. Which is out of the question, because it is too cost prohibitive for the developers. Sins is a great game, and it is a shame that this is happening. Entrenchment, and Diplomacy unintentionally pushed Sins over its own limitations with all of the new added content.
The Sins developers can not do anything to change the game at this time. However there is something that WE can do as modders to prevent Sins from hitting that dreaded 2 gig brick wall. I have taken the initiative, and applied to Sins what i have learned from my Homeworld Modding days. I present to you....

aka the "Taste Great, Less Filling" mod.
The goal of this project is to improve your Vanilla Sins game experience, and to eliminate the 2 gig crash issue. No changes will be made to Vanilla Sins gameplay at all. No stat changes will be made. Nothing will be added. There are other mods for that. We are optimizing what assets Sins already has to improve performance, and stability in game. The side benefit will be that some lower end systems can enjoy almost the same experience as the high end users.
The project initially started out as an idea to reduce the texture sizes, and poly counts of some models. Not just arbitrary reductions. The goal was to maintain the quality of Sins in game. To look like nothing has been changed at all.
As of version 0.07 there are no longer any modded planet, and skybox meshes. Unfortunately the problems caused by the unfixable mesh errors from the poly reductions were not worth what little memory was gained from those optimizations. As i said the goal was to make it look like nothing has been changed at all.
Just with a few optimizations alone the games performance had a noticeable improvement. Though not much ram was saved.
I studied the Particle files, and textures. Many of the particle textures IMO were also way to high resolution. A reduction by 1/2 showed no visible difference in game in most cases. There were some exceptions where it did effect the appearence in game, and those textures were left alone. Remember the goal was not to reduce in game quality. Also all of the particle textures were changed from TGA format to DDS format, because DDS uses far less memory, and is much more efficient. The particles also utilize the mip mapping features of DDS. Therefore enhancing in game video performance. As of version 0.07 no TGA format textures load in TSOP. With the exceptions of Mouse Cursors, and Scenario Pictures. This is due to those textures being controlled by the hard coded exe.
The developers mentioned something about a Memory Leak. I heard that a leak can be caused by a file calling for something over, and over again if it is not there. Example a mesh file calling for a texture that does not exist. Vanilla Sins has MANY particle, and mesh files that do that. I removed all of the redundant entries that pointed to non existent textures in the mesh, and particle files. I also removed the entries that have lines like "C;\gs\main\datasource\textures\effects\aura4.dds", and just put "aura4.dds". This will default the search to the mods texture folder, and speed things up. Also various typo's were corrected in some mesh, and particle files. Some ships have mesh nulls that were miss-spelled. For example the Akkan had typos on its engine nulls, and flairs. The engine trail, and flair didnt show up in game. the Marza was missing its bomb nulls. All of this has been corrected as well. If there is a ship mesh file in the mod then it had something wrong that was fixed. Regardless if this caused a memory leak, or not these errors had to be fixed.
After the Meshes, Particles, Textures, and the User Interface were optimized, and some very obvious bugs were fixed there was a tremendous boost in game performance. Sins ram usage was greatly reduced. As of version 0.07 no game i ran ever went above 1.5 gigs on Diplomacy with maximum settings. Including Bloom enabled. Tested on Huge random multi star maps with 9 AI's. The 2 gig crash problem is solved. Our primary goal with this project has been achieved! Without having to use some risky "EXE hack"!
Now TSOP is focusing on other ways to optimize the game to reduce late game lag as much as possible. Also we are searching for more bugs as part of the Community Bug Fix effort.... It's a "Bug Hunt" now 
NOTE: As of the latest Diplomacy series of patches v1.2+. Diplomacy no longer needs TSOP. Much of TSOP was incorporated into the 1.2-1.3+ series of patches. So the Diplomacy version of TSOP will no longer be linked here since it is now deemed obsolete.
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Our Website
http://soase.weebly.com/tsop.html
Some sections are still under construction
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Downloads
The Sins Optimization Project v0.08
The User Interface is completely overhauled to use pure DDS format.
Trade Ships, Strike Craft, Mines, and Constructor Unit meshes are Optimized.
Sounds, and Music are optimized.
All TGA format Textures are replaced with DDS format, and TSOP "force" loads them. The only TGA textures that remain are the Mouse Cursers, and Scenario Pictures. This is due to hard code in the EXE.
As part of the Community Bug Fix Effort, Many Mesh Null miss-labels were corrected, and Unnecessary Text Entry's were removed in both the Mesh, and Particle files. Entry's pointing to Non Existent Textures in both the mesh, and particle files removed. See the various "Fixed Files" texts in the mods Read Me for details.
The Diplomacy 1.2 graphic fix's have been incorporated into the Entrenchment, and the Original Sins versions of TSOP (Pipeline Effects, "White Line" error fix, and Corrected Mesh files).
As of TSOP 0.08 ALL textures have been reverted back to original Vanilla Sins Resolutions, but are all in DDS format. The Mip Mapping feature of DDS format "should" reduce any early game lag. Late game lag is still a problem, and is a CPU issue from too many units on the map in late game. Not a graphics issue. Graphic optimizations can not fix this.
As of the Diplomacy 1.2 patch, The issues that compelled us to create TSOP are now fixed! TSOP for Diplomacy is no longer required, and is now deemed "obsolete"! Many of the TSOP fix's, and improvements have been incorporated by Ironclad into the Diplomacy 1.2+ series of patches! We will no longer work on a Diplomacy version of TSOP. However, If we find something "game breaking" wrong with the new series of patches. Then we shall reconsider.
The Planets, Skybox's, Asteroids, Structures, Map objects, and various Other Ways to reduce the Late Game Lag issue will be looked into for any future updates.
Community input, and contributions are more than welcome, and they are encouraged! This is a Community Project! All can pitch in!
You do not need to download all versions of TSOP. You only need to download the version of TSOP for which version of Sins you wish to play. The Retail version of Trinity is just all three versions of Sins bundled into one package. Installation for Trinity versions of Sins are no different than if you purchased each version of Sins separately.

TSOP 0.08 For Original Sins v1.191

TSOP 0.08 For Entrenchment v1.051

TSOP For Diplomacy is no longer required. Since the Diplomacy 1.2 patch TSOP for Diplomacy is now obsolete.

Since TSOP Diplomacy is now obsolete. We will not host a "trinity" version.
However, when Rebellion is released we will look into what is needed (if anything at all), and perhaps make a combined version of TSOP in the future.
Add-On's, and Patches
TSOP Optional Lower Texture Resolution Add On
Optional Add On for those with VERY LOW END SYSTEMS. This Add-On "replaces" the full resolution TSOP 0.08 textures with the "strategically reduced resolution" textures from TSOP 0.07. Use this add-on ONLY if you suffer extreme graphic lag in the early game. If you still lag badly with this add on, chances are your system can not handle Sins. Use at your own risk.
Our Downloads page with optional Add-On's for TSOP
Read the Read Me's, and associated documentation for each version of TSOP, and add-on for important installation, and removal instructions. Plus other important information.
Sorry for the separate downloads. Together the project is over 600 megs with the sound, and music files, and most file host wont let you upload that much. If your download is corrupt try downloading another version. The Mesh, Particles, Textures, Sounds, and Music files are all interchangeable between each version. Replace any corrupt files with another versions files.
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This project is far from a perfect solution, and it is still rough around the edges. It is improving as time passes.
Other mods are more than welcome to use TSOP. No questions asked! In fact we encourage it! Learn from it! Use it as guide, and an example! Merge it into your projects!
TSOP is intended to be a Stand Alone mod. Run with no other mods enabled. There are issues enabling TSOP with other mods. Enabling with other "Graphic Enhancement" mods is NOT recommended, because the graphic enhancement mod will defeat the entire purpose of TSOP. All of our optimized files will be overridden by that enhancement mods "enhanced" files. Increasing your ram usage instead of decreasing it. Some enhancement mods like Distant Stars are incorporating elements of TSOP into their future updates.
Read the included READ ME text's for installation instructions.