Best Gecko-based browser for Windows 9x

The latest and last versions of Gecko-based browsers to run on Vanilla Windows 98/Me (and 95, with updates and other reservations) are

• Mozilla Firefox 2.0.0.20 (Gecko 1.8.1.20, 20081217),
• K-Meleon 1.5.4 (Gecko 1.8.1.24pre, released on 05.03.2010) and
• SeaMonkey 1.1.19 (Gecko 1.8.1.24, released on 16.03.2010).

If there were a competition between the three, then the winner would be SeaMonkey.

The reasons are thus:

• Under similar limited circumstances, SeaMonkey 1.1 is more responsive than Mozilla Firefox  2.

  Here's why: SeaMonkey 1.1's XPFE/XPToolkit-based user interface (UI) technology dates back to Mozilla Application Suite (v1.0 released 05.06.2002, but pre-releases were usable since a year before), while Mozilla Firefox 2.0 (2006) is completely based on a newer toolkit (XUL).

• SeaMonkey 1.1.19 has a newer and more secure Gecko layout engine than Mozilla Firefox 2.0.0.20 and K-Meleon.
• SeaMonkey 1.1 has been supported by the two most important extensions to grace web surfing: Flashblock and NoScript.

  K-Meleon also uses the native Windows API for its UI, meaning that it can't run extensions which normally work in SeaMonkey or Mozilla Firefox.
  
  While K-Meleon comes close with its quick UI responsiveness and its rendering engine, it's only good for websites that are safe and are known to not be resource-intensive. Most of the latter still exist as they are, but the most popular sites (for webmail and news) are regularly redesigned to include more fancy features and are therefore made more demanding by way of including extensive JavaScript and AJAX technologies and often embedding multiple manifestations of the Adobe Flash plugin.

Which is why SeaMonkey 1.1.19 adorned with NoScript and Flashblock extensions is about the best Gecko-based browser solution that there is for Windows 9x, even Windows 95.

The only caveat is that SeaMonkey requires at least 64 Mb of RAM to run passably and at least a 266 MHz CPU. Well, a Navigator-only one-window/one-or-two-tab solution works in a PC with just a slightly lesser CPU.

K-Meleon is best for computers with 32–48 Mb of RAM (certainly less than 64 Mb).
Some words of caution: Java and JavaScript could only be allowed for safe and non-demanding websites. Because of a lack of NoScript or like extension for K-Meleon, JavaScript should be turned off for casual browsing (sometimes even a Google Search result may cause a hiccup). Keeping Java on is only recommended when a user consciously recognizes a real and pressing need to use that plugin (maybe a map application over the web).

On Plugins

Although Adobe Acrobat Reader 6.0.6 (released/updated last in 2003) is about the last version for Windows 98 as far as I know, it is still outdated and so more vulnerable to attacks that use the Reader.

While older computers might best handle even older versions of Acrobat Reader, it's most important to disable Acrobat (Java)Script in the Reader's preferences, no matter the version. This should somehow prevent malicious websites using the Reader as an attack vector.

A complete alternative to using Adobe Reader in old computers is muPDF: It's much less resource intensive, supports the newest PDF document display standard (PDF 1.7) and does not use AcroScript. muPDF does not support interactive PDF elements; this is both a caveat and a security/speed measure. muPDF does capture the file type association in Windows, so when using the app, then it's an either-or situation between it and Acrobat Reader. It should still be a no-brainer in old computers.