Why should I use any other but ULTRA performance?

[Arnie_75]

I just wondered why one should choose any other setting but ULTRA? As far as I understood it's by far the fastet and has no disadvantages.

So why are the other settings (Zlib, ZRLE, etc.) included at all?

[rmoller]

I just wondered why one should choose any other setting but ULTRA? As far as I understood it's by far the fastet and has no disadvantages.

So why are the other settings (Zlib, ZRLE, etc.) included at all?

It depends whether the bottleneck is the Server CPU or the connection speed.

ULTRA uses very little CPU, but does not compress very well. It is well suited to LAN speeds (100Mbit or more).

ZRLE is an improved Zlib, will compress better, but uses more CPU (configurable setting 1-9). It is better suited for ADSL-like speeds or below.

Tight is comparable to ZRLE at max. compression, but detects pictures automatically and compress them them with JPEG (quality setting 0-9).

Automatic selection (ADSL typically -> ZRLE) works fine for me most of the time; however sometimes I switch to Tight when there are pictures e.g. internet browsing).

Hope to clarify

[Arnie_75]

OK,
I did a mistake. I meant to ask why one should use any other but TIGHT.

Today CPU performance should not be no problem anymore so is there any reason not to choose the best compression even for fast ADSL lines?

[rmoller]

Ok,

I like Tight, too, as it does give me a pretty predictable frame rate, especially over my VPN + ADSL which varies a lot in actual capacity.

However at work, the auto setting (i.e. ZRLE) gives me a noticably snappier response, so I just leave it at default.

[Arnie_75]

However at work, the auto setting (i.e. ZRLE) gives me a noticably snappier response, so I just leave it at default.

How can anything be faster than TIGHT? If TIGHT uses the best compression and if the CPU can handle it (and todays CPUs can) it should be the fastet, right?

[UltraSam]

ZRLE gives better results than Tight compression in most cases (speed/responsiveness/graphics accuracy).

As Tight uses Jpeg (lossy) compression, it gives better speed over slow connections when the screen contains a lot of graphics and pictures. But visual quality is lower than with ZRLE.
For average desktop contents (regular windows), ZRLE is faster, more accurate and less CPU intensive.

CPU load is still important, even nowadays: the longer it takes for compressing/uncompressing/displaying data, the less responsiveness you have with UltraVNC as the pace of the updates depends on viewer's requests to the server:
viewer asks for updates -> server sends updates -> viewer receives, processes and display the updates -> viewer asks for new updates... and so on.

[Arnie_75]

OK, so the two best setting are either ZRLE or TIGHT? I will try ZRLE the next time to see if it is faster than TIGHT.