hello, could you go to the firefox menu ≡ > help ? > troubleshooting information, copy the contents of that page and paste them here into a reply on the forum? this might give us a clue what is going on...

Application Basics

Name: Firefox Version: 45.0.1 Build ID: 20160315153207 Update Channel: release User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0 Multiprocess Windows: 0/2 (default: false) Safe Mode: false

Crash Reports for the Last 3 Days

All Crash Reports (including 1 pending crash in the given time range)

Extensions

Name: Adblock Plus Version: 2.7.2 Enabled: true ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}

Name: Classic Theme Restorer Version: 1.5.0 Enabled: true ID: ClassicThemeRestorer@ArisT2Noia4dev

Name: DownThemAll! Version: 2.0.18.1-signed.1-let-fixed Enabled: true ID: {DDC359D1-844A-42a7-9AA1-88A850A938A8}

Name: Firefox Hello Beta Version: 1.1.14 Enabled: true ID: loop@mozilla.org

Name: FlashGot Version: 1.5.6.13 Enabled: true ID: {19503e42-ca3c-4c27-b1e2-9cdb2170ee34}

Name: NoScript Version: 2.9.0.11 Enabled: true ID: {73a6fe31-595d-460b-a920-fcc0f8843232}

Name: User Agent Switcher Version: 0.7.3.1-signed Enabled: true ID: {e968fc70-8f95-4ab9-9e79-304de2a71ee1}

Name: app.telemetry Page Speed Monitor Version: 15.2.5 Enabled: false ID: jid0-OqxcSY9VMeMm8jJqJYy5KM0nmS8@jetpack

Name: Avast Online Security Version: 10.3.3.39 Enabled: false ID: wrc@avast.com

Name: Avast SafePrice Version: 10.3.5.39 Enabled: false ID: sp@avast.com

Name: ReloadEvery Version: 45.0.0 Enabled: false ID: {888d99e7-e8b5-46a3-851e-1ec45da1e644}

Graphics

Adapter Description: Intel(R) HD Graphics 5500 Adapter Description (GPU #2): AMD Radeon R9 M275X Adapter Drivers: igdumdim64 igd10iumd64 igd10iumd64 igd12umd64 igdumdim32 igd10iumd32 igd10iumd32 igd12umd32 Adapter Drivers (GPU #2): aticfx64 aticfx64 aticfx64 amdxc64 aticfx32 aticfx32 aticfx32 amdxc32 atiumd64 atidxx64 atidxx64 atiumdag atidxx32 atidxx32 atiumdva atiumd6a atitmm64 Adapter RAM: Unknown Adapter RAM (GPU #2): 4095 Asynchronous Pan/Zoom: none ClearType Parameters: Gamma: 2200 Pixel Structure: B ClearType Level: 0 Enhanced Contrast: 50 Device ID: 0x1616 Device ID (GPU #2): 0x6820 Direct2D Enabled: true DirectWrite Enabled: true (10.0.10586.0) Driver Date: 2-2-2016 Driver Date (GPU #2): 4-3-2016 Driver Version: 20.19.15.4380 Driver Version (GPU #2): 16.150.2211.1001 GPU #2 Active: false GPU Accelerated Windows: 2/2 Direct3D 11 (OMTC) Subsys ID: 380117aa Subsys ID (GPU #2): 0000000c Supports Hardware H264 Decoding: No; DXVA2D3D9 crashes detected in the past Vendor ID: 0x8086 Vendor ID (GPU #2): 0x1002 WebGL Renderer: Google Inc. -- ANGLE (Intel(R) HD Graphics 5500 Direct3D9Ex vs_3_0 ps_3_0) windowLayerManagerRemote: true AzureCanvasBackend: direct2d 1.1 AzureContentBackend: direct2d 1.1 AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0 (#0) Error: DXVA2D3D9 video decoding is disabled due to a previous crash. (#6) Error: DXVA2D3D9 video decoding is disabled due to a previous crash. (#7) Error: DXVA2D3D9 video decoding is disabled due to a previous crash. (#8) Error: DXVA2D3D9 video decoding is disabled due to a previous crash. (#9) Error: DXVA2D3D9 video decoding is disabled due to a previous crash. (#10) Error: DXVA2D3D9 video decoding is disabled due to a previous crash.

Important Modified Preferences

accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 1048576 browser.cache.disk.filesystem_reported: 1 browser.cache.disk.hashstats_reported: 1 browser.cache.disk.smart_size.enabled: false browser.cache.disk.smart_size.first_run: false browser.cache.disk.smart_size.use_old_max: false browser.cache.frecency_experiment: 1 browser.download.importedFromSqlite: true browser.download.manager.alertOnEXEOpen: true browser.places.smartBookmarksVersion: 7 browser.search.useDBForOrder: true browser.sessionstore.upgradeBackup.latestBuildID: 20160315153207 browser.startup.homepage: www.google.com browser.startup.homepage_override.buildID: 20160315153207 browser.startup.homepage_override.mstone: 45.0.1 browser.urlbar.userMadeSearchSuggestionsChoice: true dom.apps.reset-permissions: true dom.mozApps.used: true extensions.lastAppVersion: 45.0.1 font.internaluseonly.changed: true gfx.crash-guard.d3d11layers.appVersion: 45.0.1 gfx.crash-guard.d3d11layers.deviceID: 0x1616 gfx.crash-guard.d3d11layers.driverVersion: 20.19.15.4380 gfx.crash-guard.d3d11layers.feature-d2d: true gfx.crash-guard.d3d11layers.feature-d3d11: true gfx.crash-guard.glcontext.appVersion: 45.0.1 gfx.crash-guard.glcontext.deviceID: 0x1616 gfx.crash-guard.glcontext.driverVersion: 20.19.15.4380 gfx.crash-guard.glcontext.gfx.driver-init.direct3d11-angle: true gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle: true gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-d3d11: false gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-warp: false gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-try-d3d11: true gfx.crash-guard.status.d3d11layers: 2 gfx.crash-guard.status.d3d9video: 3 gfx.crash-guard.status.glcontext: 2 gfx.direct3d.last_used_feature_level_idx: 0 gfx.driver-init.appVersion: 42.0 gfx.driver-init.deviceID: 0x1616 gfx.driver-init.driverVersion: 10.18.15.4279 gfx.driver-init.feature-d2d: true gfx.driver-init.feature-d3d11: true gfx.driver-init.status: 2 layers.acceleration.force-enabled: true media.gmp-eme-adobe.abi: x86-msvc-x64 media.gmp-eme-adobe.lastUpdate: 1455428454 media.gmp-eme-adobe.version: 15 media.gmp-gmpopenh264.abi: x86-msvc-x64 media.gmp-gmpopenh264.autoupdate: true media.gmp-gmpopenh264.lastUpdate: 1455428457 media.gmp-gmpopenh264.version: 1.5.3 media.gmp-manager.buildID: 20160315153207 media.gmp-manager.lastCheck: 1460151906 media.gmp-provider.enabled: false media.webrtc.debug.aec_log_dir: C:\Users\Grant\AppData\Local\Temp media.webrtc.debug.log_file: C:\Users\Grant\AppData\Local\Temp\WebRTC.log media.youtube-ua.override.to: 43 network.auth.allow-subresource-auth: 2 network.cookie.prefsMigrated: true network.http.pipelining: true network.http.pipelining.aggressive: true network.http.pipelining.max-optimistic-requests: 8 network.http.pipelining.maxrequests: 8 network.http.pipelining.ssl: true network.predictor.cleaned-up: true places.database.lastMaintenance: 1460159968 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true plugin.state.npmeetingjoinpluginoc: 1 privacy.sanitize.migrateClearSavedPwdsOnExit: true privacy.sanitize.migrateFx3Prefs: true privacy.trackingprotection.enabled: true services.sync.declinedEngines: storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1459737806 ui.osk.debug.keyboardDisplayReason: IKPOS: Touch screen not found.

Important Locked Preferences

JavaScript

Incremental GC: true

Accessibility

Activated: false Prevent Accessibility: 0

Library Versions

NSPR Expected minimum version: 4.12 Version in use: 4.12

NSS Expected minimum version: 3.21.1 Basic ECC Version in use: 3.21.1 Basic ECC

NSSSMIME Expected minimum version: 3.21.1 Basic ECC Version in use: 3.21.1 Basic ECC

NSSSSL Expected minimum version: 3.21.1 Basic ECC Version in use: 3.21.1 Basic ECC

NSSUTIL Expected minimum version: 3.21.1 Version in use: 3.21.1

Experimental Features

thank you, this bit seems to be the problem:

Supports Hardware H264 Decoding: No; 
DXVA2D3D9 crashes detected in the past

you could try the following: enter about:config into the firefox address bar (confirm the info message in case it shows up) & search for the preference named gfx.crash-guard.status.d3d9video. double-click it and change its value to 2. in addition, i'd also recommend to reset all custom preferences (=shown in bold) starting with "network.http" to their respective default value.

This seems to have reduced CPU usage to about 25% at max which is a lot better. Thank you. Still not 2% but it's certainly a lot nicer.

(Also, I changed the network setting because some website say it makes Firefox faster on better internet connections. Is that just flat out wrong?)

as it is a dual gpu sytem you could also look into it if it is possible to have your nvidia gpu take over the part of rendering firefox (that may perhaps be more efficient in regards to media playback). and those recommendations to speed-up firefox at some sites are often experimental and can cause more harm than good so i'd rather dissuade you from following them...

It's an AMD GPU for the laptop and I'd change it if I could but AMD thinks they know better and lock it to the integrated GPU.