I've never noticed this on my rig when braking with either the PMDG 747 or any other a/c. I am going to test it on my rig and see if I can recreate this also.Have you tried turning of Transparency AA as Tom noted below?

I think this maybe related to the Transparency AA bug Bojote found, which caused a significant performance issue on landing. Try turning it off if it's on with your system. Since I turned mine off, performance is much more steady on landings. I just tried the test described in the linked post, with both the PMDG 744, and the default 737, and didn't see any problem. My system is an E6850 4GB and a 9800GTX card

I just love posts like relaxx, being smart without a reason that fits correctly into the topic.Try doing that with Rex, ftx and pmdg 747 landing at ksea. I get steady 30 on landing but not if I look towards the runway after landing... I get drop to 10fps.And no, I am not using transparency aa, I tried with vanilla fsx and with defaulted nvidia profile in nvidia control panel, and with all settings on lowest in fsx. Drop is always there.

I've never noticed this on my rig when braking with either the PMDG 747 or any other a/c. I am going to test it on my rig and see if I can recreate this also.

Well, I just fired up FSX and tried a landing at the default KLAX with the PMDG 747 and also again with the LDS 767 and was unable to duplicate this when braking and looking at the a/c from locked spot.I'm guessing it must be something specific to the computer, video card or drivers. Hard to know what the commonality is between those that get this FPS hit and those that don't, but I couldn't get the FPS hit when using autobrakes or manually braking in the 2 tries with both a/c.

Seems my system and Word Not Allowed's isnt really similar, but we both have this issue on vanilla FSX. This could be hard to pinpoint. He's using win7 64bit, a Nvidia card, i7, Im using XP 32 bit, ATI card, i5 My friend's low end, out of the box, non gaming computer which I tested on also had this issue. His is vista 32bit, onboard graphics, probably a core 2 or something, slow as hellcmpbellsjc, remember to test it with unlimited FPS as well, because if your running with a frame limiter, the dip probably isnt registered. I dont have aa running on my com. Hmm, maybe theres something i missed.

take the extra plane onto any airrstrip you like, switch to an external view of the aircraft, hit the brakes while applying full throttle, the created smoke will play havoc with perfomance.

hmm, well there isnt any smoke for me, but the braking with the extra also creates the same problem. EDIT: I found something interesting. If braking was done on a wet runway, eg it's raining or snowing and the runway is the reflective surface, I dont get the fps drop! I found a long runway, put on rain, Did an RTO for half of it, (fps 50 -> 50 average no drop), then I switched to clear skies, (fps now 70) Used the other half for a dry RTO, (fps dropped to 30) Switched back to rain, (fps now 20) Note: lower fps during rain on average, due to clouds/weather effects, but you can see, the impact is on dry ones. Is this the same for you all?Could it be due to the difference in wet/ dry runway modeling? The contact physics, mist effect on wet runways?

UPDATE:I think I have narrowed this thing down. I suspect something in the effects folder is screwing things up. For a test, I removed all the effects files fx_blahblah.fx, except for the cfg file, from the FSX folder into a temp desktop folder. Testing braking on normal dry runway, with the PMDG 747 and 737, no fps hit, nothing. I did it as per my first post, but the bug is no longer there. Looks like one of the fx files is acting up.Now i will slowly put the fx files back into the folder one by one until the problem comes back, to identify the file. Though removing it will probably come at an expense of lost effects, whatever that effects file was meant to do. I will update again once I find out. It appears this problem could be solved.

Good detective work, Bamboofats!Curious to see which fx file is the guilty one.

GAHHH, found the offending thing.Its called fx_skidmark.fx, located inside the main FSX effects folder. A file called skidmark cant be any good when it isn't actually providing any visible effects.Trashed it and now, no more fps drops, with hardbraking, on dry or wet runways. Problem solved, for me at least. If you feel you have no need for skidmarks(are they actually rendered?) , and are experiencing this problem as well, by all means get rid of the file. See if it helps you.Anyway thanks everyone for getting involved. If no one had reported having this same problem as me I would have thought it was my own rig problem and probably wouldn't have bothered fixing.

Glad to see that you figured out what is causing it. I checked my directory and do have the same fx file, but for some reason I dont get the FPS impact that you did.

cmpbellsjc, remember to test it with unlimited FPS as well, because if your running with a frame limiter, the dip probably isnt registered. I dont have aa running on my com. Hmm, maybe theres something i missed.

When I tested it on my rig it was with unlimited FPS. I never use an external frame limiter and always fly with FPS set to unlimited when using planes like the PMDG 747 or LDS, however when flying small planes that aren't resource hungry then I have to lock FPS around 30 otherwise they bounce around to much.Anyways, glad you figured it out. Like you I wonder what that effect actually does since I have never seen FSX actually render a skid mark when landing?

yea, It kind of makes sense now what was causing this bug. Seems skidmarks were supposed to be drawn during braking, perhaps only on dry runways, and there were meant to disappear after a few minutes. Probably microsoft thought the effect was ugly or something and disabled it, but not completely and the effect was still being produced, but now its invisible. I have seen one or two touchdown/ smoke effect addons that apparently introduces the skidmark effect though, I think they would have modified this file.Perhaps for the benefit of others who may have this issue, this fix could be placed in one of those tweak guides or something. Of course ppl having the same problem as me like Word Not Allowed should verify it works first.

UPDATE:I think I have narrowed this thing down. I suspect something in the effects folder is screwing things up. For a test, I removed all the effects files fx_blahblah.fx, except for the cfg file, from the FSX folder into a temp desktop folder. Testing braking on normal dry runway, with the PMDG 747 and 737, no fps hit, nothing. I did it as per my first post, but the bug is no longer there. Looks like one of the fx files is acting up.Now i will slowly put the fx files back into the folder one by one until the problem comes back, to identify the file. Though removing it will probably come at an expense of lost effects, whatever that effects file was meant to do. I will update again once I find out. It appears this problem could be solved.

well done!I think it's time to gather all those little tweaks in a single thread that should be pinned at top of the fsx forum!

Solved for me too! Thanks very much Bamboofats!

You had discovered a great thing!Thank you for your effort.This topic should be made sticky.

Good find... another loose end wrapped up :(