On my 64bit Ubuntu 12.04 on an Intel Core i3 processor which has 16Gb RAM and a M4 SSD, NetBeans is very sluggish as well as the known problem where NetBeans does not use Ubuntu 12.04's global menu. That problem aside, why is NetBeans so slow, it's even slower than Eclipse!

Please have a look at this video: http://youtu.be/utLQD5Gpg0M

  • I don't think your menu example is an accurate metric for sluggishness. It's waiting for a mouse hover from what I can tell. If you really want to test it for "sluggish" open one of the menus and tap left or right arrow-keys to see how much lag there really is. Jun 27 '12 at 20:53
  • I have never seen NetBeans running much faster than that. I think that's just the way it is (I can't imagine what it does in the background to achieve that awful performance...)
    – marcus
    Jul 3 '12 at 0:27

Look & Feel:

GTK+ and Java Swing Applications do not play well at all together when it comes to look and feel. I am afraid we'd have to wait for Java 8 for a proper fix.

For the time being, if you're not using Kubuntu but Ubuntu and Unity, you have to switch to the native look and feel which is Metal.

Go to your netbeans directory (ex: /home/user/netbeans7.2/etc) and open the file : netbeans.conf

then add the following line to netbeans options:

-J-Dswing.aatext=true -J-Dawt.useSystemAAFontSettings=lcd --laf Metal

Netbeans in Ubuntu 12.04 using Metal LAF

Source: http://hanynowsky.wordpress.com/2012/04/27/netbeans-ide-look-feel-under-ubuntu-12-04/

Global menus: Java Swing applications cannot benefit from Global menus integration for now. For the same reason: GTK/Swing implementations. Even Eclipse IDE is blacklisted for now even though it's SWT and not Swing based. Same goes for Emacs and Lotus notes. Nevertheless, you can activate Global Menu support for Java Swing applications by using Java Ayatana Library and for netbeans install the corresponding plugin : http://hanynowsky.wordpress.com/2012/05/12/integration-of-java-swing-applications-with-unity-global-menu-in-ubuntu-12-04/ By the way, it would be ideal if OpenJDK crowd include this same library in OpenJDK's next version so that Swing Application get support for Global Menu out of the box.

Slowliness: I use Netbeans IDE frequently on my machine and it's not slow at all compared to Eclipse. It might be an issue with the version packaged for Ubuntu Software Center (repos). I don't recommend it. Instead, download Netbeans 7.1.2 from Netbeans.org and install it locally on your home directory. You'll notice that it's faster than the version in repositories. Slowliness might also occur when you're using OpenJDK instead of Oracle JDK (Tested).

  • Thanks, this sorts out the visual issues, but the slowness is still there. For some reason, Aptana and Eclipse load on my computer fully ready to use within a second with no lag. But Netbeans takes a good 5 seconds I would say and then is laggy for another 3 seconds after loading, after which it is OK. May 9 '12 at 18:33
  • you're welcome! But what version of Netbeans are u using? What JDK? For me, Netbeans takes some time to load all the modules before starting and then scans all the projects. In total: 15 seconds for Netbeans and 14 s for Eclipse.
    – Hanynowsky
    May 10 '12 at 20:44
  • I am currently running NetBeans 7.0.1, but I have also tried NetBeans 7.1.2 which doesn't seem to make a difference in terms of speed. I am running java 1.6.0_24: java version "1.6.0_24" OpenJDK Runtime Environment (IcedTea6 1.11.1) (6b24-1.11.1-4ubuntu2) OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode). Also, it takes about 11 seconds in total to load from scratch to becoming usable. Just as a comparison, Libre Calc takes less than a second on my new SSD... May 11 '12 at 18:43
  • If you run LibreOffice for the second time, yes it takes less than a second. I have an i7 2.10hz with 4 Go of RAM and netbeans takes 15s to be ready which is pretty normal (netbeans is a huge IDE full of modules).
    – Hanynowsky
    May 11 '12 at 20:06
  • 1
    Know also that NetBeans is very memory-hungry! Check if OpenJDK has bootstrapping parameters that can be called from netbeans.conf . I would check and if I find something. I'd report to u!
    – Hanynowsky
    May 11 '12 at 20:11

This seems to be a problem of the default Adwaita theme (and probably others as well). The gtkrc for GTK2 application causes problems to GTK LAF and prevents rendering separators and menu borders. Obviously, in some cases it may also cause UI sluggishness (even though I haven't experienced it)

By tweaking the gtkrc file I was able to resolve the problem.


Replace the following 3 style sections in the gtkrc :

style "menu" {
    xthickness = 1
    ythickness = 1

    bg[NORMAL]        = shade (1.08, @bg_color)

    engine "clearlooks" {
        radius = 0.4

style "menu_item" {
    xthickness = 2
    ythickness = 3

    fg[PRELIGHT]      = @selected_fg_color

# This style is there to modify the separator menu items. The goals are:
# 1. Get a specific height.
# 2. The line should go to the edges (ie. no border at the left/right)
style "separator_menu_item" {
    xthickness = 1
    ythickness = 1

    GtkSeparatorMenuItem::horizontal-padding = 0
    GtkWidget::wide-separators = 1
    GtkWidget::separator-width = 1
    GtkWidget::separator-height = 7

I've just upgraded to Kubuntu 12.04 and there is no problem with NetBeans IDE what so ever. The reason my be that Kubuntu is KDE based distribution and NetBeans IDE is by default using Metal L&F.

In my opinion, you can improve your NetBeans experience under GTK by forcing it to use Metal L&F. The command line options is --laf Metal (or something like that).


Try using those switches in netbeans.conf

-J-XX:ReservedCodeCacheSize=1024m -J-XX:+UseCodeCacheFlushing

You can give less memory to ReservedCodeCacheSize (default is 64m) but on my system with lots of RAM this switch made Netbeans suddenly much faster.


On Kubuntu 12.04 and I had to reinstall twice in order to get netbeans to load and run. I have experienced major degradation of performance. When I type, it takes seconds for to register.

This is why I've switched to mac at home.

  • I have no problem using it with regular ubuntu aside from it not using ubuntu's global appmenu. I'd say it's not that OSO quality has gone to crap but more like "we expect commercial quality of OSO"
    – T0xicCode
    May 7 '12 at 17:02
  • So what would the solution be here? Netbeans was snappy on 10.04. May 7 '12 at 17:11
  • xav0989, If it wasn't for the quality of OSO in previous releases of Ubuntu where NetBeans worked very responsively, I would have agreed with your comment. May 7 '12 at 19:57
  • 1
    @Jesse a recent study confirmed that open source software code quality has surpassed its rival in proprietary software!
    – Hanynowsky
    May 10 '12 at 20:48
  • @Hanynowsky That is true however I prefer a system where both hardware and software are taken into consideration when being developed. i.e. Apple products.
    – Jesse
    Jun 6 '12 at 19:16

I had a problem with Netbeans ceasing to respond to keyboard and mouse input. Had to use xkill several times a day, losing work in the process. I upgraded to Netbeans 7.1 (not in the repositories, but a very simple upgrade) and have not experienced this issue since. I hope this helps someone with similar frustrations.


Put your .netbeans Homefolder into a Ramdisk as I mentioned here.


It's been a long time since this question has been asked, but I do experience sluggish behaviour with Ubuntu 20.04.1 LTS and Netbeans 8.2.

I tracked down the problem to be a graphical one, as others suspected as well. I have not found a solution yet, but a workaround that works for my case : the UI gets unresponsive seldomly.

The workaround is to change the font size in Tools > Options > Fonts & Colors. Whatever you profile is, change the font size. I personnaly use 24, and set it to 26, then all is OK until the next restart. Then, change it back to 24. I allows me to use Darcula, by the way.

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