Some dynamic pages loading broken

[UserHuge]

Hi for a long time some pages stopped loading properly, so I used to go around by using Chromium for those particular tasks. Anyway, it's too much already.
Concrete pages that won't load: https://wordpress.com/post/ -- Trying to write a new post to my blog ends in the "Beep beep boop" loading indicator infinitely.
: Doodle used to not work at all with a bunch of error messages on the(ir) page, now works with a huge warning saying
"Doodle requires cookies and local storage support to be enabled.
Please check your browser settings. Click here to learn how
» Click here to reload this page"

I really need to want to work with the Wordpress. I already tried deleting cookies, which wouldn't help, I suppose its some of my (acive )plugins/addons:
Software:Firefox 30.0 (20140605174243)
OS:WINNT (x86-msvc)

-Adblock Plus 2.6.3
-Add-on Compatibility Reporter 2.0.4
-Addon List Dumper (restartless) 0.1
-British English Dictionary 1.19.1
-ChmFox 2.9
-Citrix Online Web Deployment Plugin 1.0.0.104 1.0.0.104
-Copy ShortURL 2.1
-Default Full Zoom Level 7.0.5
-Diigo Toolbar 5.1.0.38
-DownloadHelper 4.9.22
-FireGestures 1.8.7
-FlashGot 1.5.6.1
-Flashblock 1.5.17
-Foxit Reader Plugin for Mozilla 2.2.3.111
-Google Earth Plugin 7.1.2.2041
-Google Update 1.3.24.15
-Hide Find Bar 1.3.1
-IE Tab 2 (FF 3.6+) 5.12.12.1
-IE Tab Plug-in 2.2.0.1
-Java Deployment Toolkit 7.0.130.20 10.13.2.20
-Java(TM) Platform SE 7 U13 10.13.2.20
-Lazarus: Form Recovery 2.3
-Memory Fox 7.4
-Menu Editor 1.2.7
-MinimizeToTray revived (MinTrayR) 1.1.2
-Mozilla Archive Format 3.0.2
-Multiple Tab Handler 0.7.2014050101
-OnLive Games Service Detector for Firefox 1.0.7.11356
-Photosynth 1.1.0.3860
-Picasa 3.0.0.0
-Print Edit 12.8
-QuickTime Plug-in 7.6.2 7.6.2.0
-Restart Firefox 0.5
-Restartless Restart 9
-Resurrect Pages 2.0.6
-Shockwave Flash 11.9.900.170
-Silverlight Plug-In 5.1.20125.0
-Simple Timer + Clocks 1.4.1
-Správce relací 0.8.1.3
-Status-4-Evar 2014.05.03.06
-Tab Counter 1.9.9
-Tab Mix Plus 0.4.1.4pre.140613a1
-Tabs Always In Titlebar 1.2
-Toolbar Buttons 1.0
-Tree Style Tab 0.14.2014051101
-VLC Web Plugin 2.1.3.0
-Výchozí 30.0
-Windows Live™ Photo Gallery 15.4.3508.1109
-Windows Presentation Foundation 3.5.30729.1
-Wolfram Alpha Google 1.1
-Wolfram Mathematica 8.0.31.46148
-gTranslate 0.9
-keyconfig 20110522

Any idea, what could be the cause?

[LoudNoise]

First, I would try Firefox safe mode. This is a testing mode that restarts Firefox without loading extensions or themes (and a few other things) On the keyboard, type ,Alt, H. Click on "Restart with add-on..." . Click on the Restart button.

[UserHuge]

OK..! So I thought I tried the no-addons mode before, but it seems to not fix the wordpress.com/post problem. (Also the Doodle nag-message still appears.)
Yet I can hardly believe that such a big webApp as Wordpress is would not be compactible with Firefox 30, I run. Any other suggestions?

[JayhawksRock]

Did you try disabling all plugins except maybe Flash ? They are not disabled in Safe Mode..

[UserHuge]

Yea, I thought about that too, but guess what -- After starting back to normal session both Wordpress and Doodle run just fine!
Classical exemplary case of a ghost( or mystery) bug..!

And thanks for suggestions, guys.

EDIT: While I can start a new post in Wordpress it lags forever the old way when trying to save the post.