The module known as "The Last Days Of The Third Age" is one of the most popular Mount & Blade mod and, despite featuring massive settlements, its scenes have always been very performance friendly thanks to a fine work of optimization.

With the update of November 28th 2021 (revision 3564), however, mod developers decided to replace their old Minas Tirith with a new one from an scene pack made by "In_Vain". Unfortunately, while this version matches better the Tolkien depiction (because it has black walls) it caused my FPS to dramatically drop.

This FPS drop is the only one I experience with the mod, and it happens because of a GPU bottleneck (core used at 100%). The card used is an MSI NVidia GTX 980Ti Reference with both memory and core clocks overclocked at +180MHz (and with max voltage and power target set).
Unfortunately the scene is used in many battles that may take place nearby the white city during the campaing and, if you attempt to make a siege there, then your computer may give some problems.

To date I received no answer to my plea in the discussion section of the mod's workshop page (https://gtm.steamproxy.vip/workshop/filedetails/discussion/299974223/3184612071863521162/) and my message on the comment section got deleted; I fear that a patch for this isn't coming anytime soon. Because so, here follows a guide step-by-step on how to reverse Minas Tirith on your own installation.

It is needed to download the unpatched 3.6 version of the mod, without any revision. This can be done only via the Bitbucket (https://bitbucket.org/Swyter/tld-downloads/downloads/TLD_3.6_wb.7z) link in the mod's github website (https://tldmod.github.io/).

Once the unpatched version of the mod has been downloaded, unzip it and located inside it the directory "SceneObj" so to find, among the others, the following 7 files:

scn_minas_tirith_castle.sco,
scn_minas_tirith_center.sco,
scn_minas_tirith_center_mid.sco,
scn_minas_tirith_center_top.sco,
scn_minas_tirith_outside.sco,
scn_minas_tirith_siege.sco,
scn_minas_tirith_siege_inner.sco;

copy these map files and past them (prompting "yes" for overwriting) into the "SceneObj" directory of your working mod folder (id est the folder where you have installed your updated and working copy of "The Last Days Of The Third Age", which can be in your "[...]\MountBlade Warband\Modules\" directory if you have manually downloaded the mod or inside "[...]\steamapps\workshop\content\48700\299974223" if you subscribed to the Steam workshop item).

Still in your working copy of the updated mod's version there should be a file called "scene_props.txt", open it and find the following lines:

spr_gondor_citadel_main 0 0 gondor_citadel_main_2 bo_gondor_citadel_main_2 0

spr_gondor_citadel_main_E 0 0 gondor_citadel_main_2 0 0

replace then these two lines with these ones:

spr_gondor_citadel_main 0 0 gondor_citadel_main bo_gondor_citadel_main 0

spr_gondor_citadel_main_E 0 0 gondor_citadel_main 0 0

Now locate the file "scene.txt", always within your working copy of the mod, and replace this:

outer_terrain_plain
scn_minas_tirith_center minas_tirith_center 256 none none 0 0 200 200 -100 0x0000000330000500000d234800007e03000001780000021b
0
0
New_outer_terrain_tirith_2
scn_minas_tirith_center_mid minas_tirith_center_mid 256 none none 0 0 200 200 -100 0x00000007300005004009c5a200000f5200005bd50000739d
0
0
New_outer_terrain_tirith_2
scn_minas_tirith_center_top minas_tirith_center_top 256 none none 0 0 200 200 -100 0x0000000330000500000d234800007e03000001780000021b
0
0
New_outer_terrain_tirith_2
scn_pelargir_center pelargir_center 256 none none 0 0 200 200 -100 0x00000006300005004009c5a200000f5200005bd50000739d

with this:

outer_terrain_plain
scn_minas_tirith_center minas_tirith_center 256 none none 0 0 200 200 -100 0x00000007300005004009c5a200000f5200005bd50000739d
0
0
outer_terrain_tirith_1
scn_minas_tirith_center_mid minas_tirith_center_mid 256 none none 0 0 200 200 -100 0x00000007300005004009c5a200000f5200005bd50000739d
0
0
outer_terrain_tirith_1
scn_minas_tirith_center_top minas_tirith_center_top 256 none none 0 0 200 200 -100 0x00000007300005004009c5a200000f5200005bd50000739d
0
0
outer_terrain_tirith_1
scn_pelargir_center pelargir_center 256 none none 0 0 200 200 -100 0x00000006300005004009c5a200000f5200005bd50000739d

Finally, find the the file "menus.txt", again inside your working and updated copy of the mod, and within it replace this:

Climb_up_to_the_top_level. 6 2133 2 144115188075856058 221 2133 2 144115188075856059 221 1911 1 2 1912 1 4 1910 1 31 2048 0

with this:

Climb_up_to_the_top_level. 5 2133 2 144115188075856058 221 2133 2 144115188075856059 221 1911 1 2 1910 1 33 2048 0

Everytime save the changes, but make sure to make a backup (otherwise you can always just overwrite the files of your manually installed working and updated copy of the mod from the files of the last revision available at https://tldmod.github.io/ or, if you subscribed to the Steam workshop item, unsubscribe, delete the folder "299974223" inside /steamapps\workshop\content\48700\" and subscribe again).

There are many mods for many games that include heavier and lighter versions of certain critical assets, a Mount & Blade example is the "Sands Of Faith" leggendary mod set in the era of the crusades (https://www.moddb.com/mods/sands-of-faith/downloads/sof-23-optional-patch-complete and https://www.moddb.com/mods/sands-of-faith/downloads/sof-23-optional-patch-partial); I'd suggest for this mod to create an optional patch including all the more heavy scenes from the In_Vain pack, or viceversa to make available a legacy patch for users without a gear updated to the very best and modern components.