This is a gif of the flickering and the sluggish interface:
https://dl.dropboxusercontent.com/u/51891186/22.gif

The first part is the full screen issue, recording a part of my screen, after 
that, I record the bottom part of the screen (where the scrolling text appears 
in the interface) to show how slow it is. You may not notice it in the gif, but 
scrolling around in the starmap while holding the right button is MUCH 
smoother, while doing this on the planet's surface is extremely choppy.

Hello and thanks for the report.

Sluggishness: By default, the game screen refreshes itself on 10-20 FPS to save 
on CPU and graphics power consumption, especially on laptops; but if you 
interact with the game through scrolling, it will go as fast as your hardware 
permits. You can increase the game speed which will increase the FPS output. 
The DOS game had similar slow framerates, but it was hidden as the scroll speed 
was capped as well.

Flickering: this looks very strange; it seems that if you go to full screen, 
Win 8 constantly switches between desktop and fullscreen. Do you run any other 
application in the background that could do this? Try maximized window instead 
of full screen. 

Just one other remark: I think yours is a hybrid graphics laptop: an Intel + 
NVidia combo. You could try forcing java.exe to always run on one or the other 
via NVidia panel I think.

My laptop running on Win 7 with as you said a Intel + NVidia combo has the same 
behaviour. By default java.exe run with the Intel chipset on my computer. 
Unfortunately, for me, forcing java.exe to always run with Nvidia doesn't solve 
the issue.

Maximized window works well.

@benjamin since when do you get this issue?

I tried the game on a virtualized Win 8 and I have an Intel+Radeon laptop which 
didn't show this effect.

Could you both try launching the game in windowed mode, quit other applications 
including the launcher and see if the fullscreen toggle still produces this?

I already had the issue with the 0.95.152. I don't remember if it happened in 
earlier versions. I didn't report because I thought I was caused by a lot of 
application running on the same time on my laptop.

Closing every applications on the foreground make any difference. Obviously 
there still a lot of background applications I didn't shut down.

Ctrl+Alt+Suppr then Escape every time Open IG is started is the best way to 
shut this effect. 

Also, sometimes, the keyboard doesn't respond anymore after switching between 
windowed and fullscreen or vice versa.

So, this issue could have a link with Issue 794: Keys unresponsive

True, I have this hybrid setup. I've already tried all the trivial stuff, such 
as forcing the Nvidia GPU (I already had it setup like that to ensure max 
speed).

Increasing game-speed does not help with the choppyness, it just makes it 
"chop" faster if you know what I mean, still leaving that frame skipping within.

I also tested it on my main Windows 7 32-bit computer (i5 650 @ 3,2ghz, 
Sapphire Radeon HD6870, 4gb RAM), which showed the same results regarding the 
choppy interface.

I've already circumvented the full screen issue by simply turning it off and 
playing in maximized window mode, it's not a big deal to me :P


Now some interesting stuff:
I fired up the old Imperium Galactica on DosBox to see the differences, and 
there were some notable ones. For instance, the interface animations are silky 
smooth, besides the bottom scrolling bar, which is still smoother than open IG 
though. 

I ran the game with 40000 cpu cycles in DosBox, vga mode with double scaling 
rendered by direct draw.

Then I went to planet view, and I immediately noticed what was my issue with 
open IG's planet view: 

-In the original game, scrolling was snapped to tiles, it looked choppy, but it 
was consistent, so it didn't feel that bad.
-In open IG scrolling doesn't seem to tie to tiles, but is very choppy and 
inconsistently so, I'd rather have the tile snapping than a choppy free cam.

Also, space battles in the DOS version are extremely smooth, while the ones in 
open IG can barely be taken seriously (it looks like 5-9 frames per second or 
so).

I hope this information was of any use, I'm a huge fan of your project, I think 
that putting effort into making it run fully smoothly on modern systems will 
really boost its popularity, because in my eyes the game hasn't aged at all.

@benjamin: thanks, I think I managed to fix the unresponsive keys.

The choppy behavior is due to the programmatically limited framerates. The 
default is 10 frames per second. Unfortunately, this is partly due to Java and 
other technology limits. If I'd known OpenGL back then, there wouldn't be any 
such issues, but now it's late.

For the full-screen flickering, I don't know how to avoid it, could be some 
hardware specific thing. Try what benjamin suggested: CTRL+ALT+DEL and cancel. 
I'll update the troubleshooting page.