The report is too generic. A lot of issues are already known, and developers will work on it if they have time. KDE SC 4.5 is going to be a "polishment" release for some applications like Plasma.

Developers are aware of this performance bugs, they do not introduce slowness in purpose; but sometimes there is too much work and a few helping hands.. help is always needed in here. (http://kde.org/community/getinvolved/)

About the video:
- You can disable the menu slide animation in SystemSettings (so it will popup inmediatly if you don't like/use the effect)
- system:/ was dropped in KDE SC 4 because nobody ported it... and it is unrelated to performance (in this case) (lack of manpower)
- I'm not really sure if "time" can be objective/useful when trying to benchmark GUI apps.. (I'm not a real expert on this topic...)
- KHTMLPart seems to be slow when loading the background image (on Konqueror/KInfoCenter)

----

- Is there any other issue you noticed ? Could you write them down ?

Thanks for your feedback

For future reports, try to also write down the bugs you noticed. Also, try to not mix different issues in the same bug report.

Yes, you understand right. That's all issues. :-)

- I didn't meant that I don't like the menu slide animation, but you can see that it is slow.

- Yes, system:/ isn't related with the performance, the video is a first of this comparative:
-- http://www.youtube.com/watch?v=NpFIbYAIi9A (edited since you last visit with minor changes)
-- http://www.youtube.com/watch?v=Njjyzh9vRvg
I think that this KIO-slave must be ported for KDE 4.5, for better user experience, because all things are in one site.

- I don't know if "time" command is objetive, but as you can see in the second video, in GNOME shows less resposive time and GNOME loads the programs in less time.

I understand that create a desktop environment KDE 4 is a hard work, but I can't understand the reason that primary things (like performance) are in second plane.
I was a KDE 3 user in the past, but KDE 4 forced to me to use GNOME. I like KDE community and the desktop ideology (in GNOME, anything confuses to the user and they doesn't implement interesting features), and KDE 4.4 is the first real solid (but not rock) desktop for the 4 series. But, sincerely, I can't use or recommend it because the poor performance that it has.

I hope that, as you say the performance will be the first priority for KDE 4.5, not all people have an Intel's Core i7 CPUs.

I collaborated with KDE with money, bug reports, mockups and little icon packs for some application to integrate non-KDE applications with KDE. I also have KDE/Plasma T-Shirts, like a good freak :-)
I know that it's no very much, but I can't collaborate more, I am not a developer.

I'm sorry for this big comment, and I see us again on KDE 4.5!

First of all: thanks for all the feedback and for your different contributions to KDE :)

Some notes:
- May be you want to create a bug report for "bringing back" the system:/ kioslave

- About the Plasma menu sliding effect, may be it could be configuration to setup the delay in ms, or made a bit more quicker by default (that should be reported against "plasma")

- I use KDE SC 4.5 trunk on a Celeron 1.8ghz and the performance is quite acceptable. Sometimes the hardware (or the drivers) are involved in this. 
It was said many times that Qt4 uses more Xorg stuff that wasn't too much tested/optimized previously, causing some performance bugs when drawing. (you can note this if you run KDE or Qt apps with the raster graphics engine (drawing by software). as example: run "konqueror -graphicsssytem raster" .. it will load and show the image a bit more faster)

- I know and recognize all the problems the KDE Software currently has, and I do my best to try to help reverting the situation. (at least when working with bug reports and fixing small bugs)

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About this specific bug report, I would suggest to split up the different issues into different bug report against the proper products. There were too much "kde4 is slow" reports in the past, and I doubt we can make something with them. as "kde4 is no more slow" will involve a *lot* of things and improvements everywhere.

- What do you think ?

Regards

You're welcome.

About the Plasma menu sliding effect, I don't say that is low as "slow", is slow "as jumps", as you can see in the video.

I test KDE SC 4.4 in three different computers, and in another two of my firends. Different hardware for the same result. They (and me too) was KDE 3 lovers, but now they said something like this: It's very pretty, I like it, but I can use dialy with this issues, ¿can't install KDE 3, why?).
Because this reason (and also because the current distros don't include KDE 3), they are using GNOME, and probably they will never like know anything about the pretty KDE 4.
Or that is the same: KDE will be only for minority users (almost computer's tehcnicians at least), GNOME will be for the most users and for empresarial areas.
About KDE 4.5, will be the last promise for me and 4 series. I think that in 2,5 years the desktop will be ready for all users, like as happened with Windows Vista -> Windows 7. If KDE 4.5 is not ready for the desktop, I don't know when it will be, and I switch to GNOME definitely.

If we want people to have confidence again, this can not be repeated anymore (in KDE 5.0, for example). Best bit and well (GNOME), that much and badly (KDE 4). This is the maxim that KDE must follow in the future, and don't forget it for KDE 5.0.
Desktop environments are for pleople, not for to do experiments.

I created the system:/ KIO-slave report since... ¿a year ago? The answer was as you say: the author is missed and it doesn't port it (O.K., this tool isn't goes to exist anymore? -I thought-).

About the slowness charge of the images in KHTML KPart, I will not report it, it's very evident and I sure that KHMT KPart's developer(s) opens Konqueror every day.
IMHO, KHTML had to be replaced by WebKit in KDE 4.0 instead of working in a old and uncomplete HTML engine and duplicate efforts unnecesarily.

You have nothing to thank me, but I have to thank to KDE developers for KDE 3, that it was nice while it lasted.

Like Porky says: That's all friends!

Marking as REMIND as the report doesn't describe a particular issue but a couple of situations. (I don't want to mark it as INVALID as it wont make sense in this case)
@usr: I already replied you by mail with some hints/help.
Regards