Computer suddenly got slower.

Hello. I've been playing alot of computer games during my time with this computer, and it all ran extremely smooth and the fps was very high. But one day all out of sudden, i noticed my computer started to slow down sort of. It went from 300-400 fps on League of legends, to 100-200. Sometimes the computer is really slow and gets back to normal after i restart it. When the computer is very slow i end up getting 30-40 fps on league of legends. I cant say this have happened after downloading or changing anything because i cant really remember, but i dont think i did anything to provoke it. Im not smart when it comes to computers, so if you have any tips try to keep it simple please .

Edit: It also seems like my computer is opening stuff slower, and its quite laggy in general, but nothing too much

I would really appreciate your help!

Here are my specs.
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System Information
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Time of this report: 10/1/2016, 21:18:58
Machine name: SIDFRAISTID-PC
Operating System: Windows 7 Ultimate 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.110408-1631)
Language: Norwegian (Bokmål) (Regional Setting: Norwegian (Bokmål))
System Manufacturer: MSI
System Model: MS-7693
BIOS: BIOS Date: 05/29/14 16:45:50 Ver: 04.06.05
Processor: AMD FX-8370E Eight-Core Processor (8 CPUs), ~3.3GHz
Memory: 8192MB RAM
Available OS Memory: 8140MB RAM
Page File: 6124MB used, 10154MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.01.7601.17514 32bit Unicode

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DxDiag Notes
------------
Display Tab 1: No problems found.
Sound Tab 1: No problems found.
Sound Tab 2: No problems found.
Sound Tab 3: No problems found.
Input Tab: No problems found.

--------------------
DirectX Debug Levels
--------------------
Direct3D: 0/4 (retail)
DirectDraw: 0/4 (retail)
DirectInput: 0/5 (retail)
DirectMusic: 0/5 (retail)
DirectPlay: 0/9 (retail)
DirectSound: 0/5 (retail)
DirectShow: 0/6 (retail)

---------------
Display Devices
---------------
Card name: AMD Radeon R9 200 Series
Manufacturer: Advanced Micro Devices, Inc.
Chip type: AMD Radeon Graphics Processor (0x67B1)
DAC type: Internal DAC(400MHz)
Device Key: Enum\PCI\VEN_1002&DEV_67B1&SUBSYS_E285174B&REV_00
Display Memory: 3791 MB
Dedicated Memory: 4072 MB
Shared Memory: 3814 MB
Current Mode: 1366 x 768 (32 bit) (59Hz)
Monitor Name: Generisk PnP-skjerm
Monitor Model: TOSHIBA-TV
Monitor Id: TSB0108
Native Mode: 1920 x 1080(p) (50.000Hz)
Output Type: HDMI
Driver Name: aticfx64.dll,aticfx64.dll,aticfx64.dll,aticfx32,aticfx32,aticfx32,atiumd64.dll,atidxx64.dll,atidxx64.dll,atiumdag,atidxx32,atidxx32,atiumdva,atiumd6a.cap,atitmm64.dll
Driver File Version: 21.19.0134.0001 (English)
Driver Version: 21.19.134.1
DDI Version: 11
Driver Model: WDDM 1.1
Driver Attributes: Final Retail
Driver Date/Size: 9/7/2016 17:47:48, 1546712 bytes
WHQL Logo'd: Yes
WHQL Date Stamp:
Device Identifier: {D7B71EE2-24F1-11CF-FA74-03C2BCC2D835}
Vendor ID: 0x1002
Device ID: 0x67B1
SubSys ID: 0xE285174B
Revision ID: 0x0000
Driver Strong Name: oem23.inf:ATI.Mfg.NTamd64.6.1:ati2mtag_Hawaii:21.19.134.1ci\ven_1002&dev_67b1&rev_00
Rank Of Driver: 00E62000
Video Accel: ModeMPEG2_A ModeMPEG2_C ModeVC1_C ModeWMV9_C
Deinterlace Caps: {6E8329FF-B642-418B-BCF0-BCB6591E255F}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,1) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{335AA36E-7884-43A4-9C91-7F87FAF3E37E}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_BOBVerticalStretch
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{6E8329FF-B642-418B-BCF0-BCB6591E255F}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,1) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{335AA36E-7884-43A4-9C91-7F87FAF3E37E}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_BOBVerticalStretch
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(YV12,0x32315659) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{A491560E-FFE4-4202-9B1D-2DCD004EB9E3}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,2) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{3C5323C1-6FB7-44F5-9081-056BF2EE449D}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,2) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{552C0DAD-CCBC-420B-83C8-74943CF9F1A6}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,2) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{6E8329FF-B642-418B-BCF0-BCB6591E255F}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,1) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{335AA36E-7884-43A4-9C91-7F87FAF3E37E}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_BOBVerticalStretch
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(IMC1,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(IMC2,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(IMC3,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(IMC4,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(S340,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(S342,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
D3D9 Overlay: Not Supported
DXVA-HD: Not Supported
DDraw Status: Enabled
D3D Status: Enabled
AGP Status: Enabled

-------------
Sound Devices
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Description: Hodetelefoner (High Definition Audio-enhet)
Default Sound Playback: Yes
Default Voice Playback: Yes
Hardware ID: HDAUDIO\FUNC_01&VEN_10EC&DEV_0900&SUBSYS_1462D693&REV_1000
Manufacturer ID: 1
Product ID: 65535
Type: WDM
Driver Name: HdAudio.sys
Driver Version: 6.01.7601.17514 (Norwegian (Bokmål))
Driver Attributes: Final Retail
WHQL Logo'd: Yes
Date and Size: 11/20/2010 12:44:23, 350208 bytes
Other Files:
Driver Provider: Microsoft
HW Accel Level: Basic
Cap Flags: 0xF1F
Min/Max Sample Rate: 100, 200000
Static/Strm HW Mix Bufs: 1, 0
Static/Strm HW 3D Bufs: 0, 0
HW Memory: 0
Voice Management: No
EAX(tm) 2.0 Listen/Src: No, No
I3DL2(tm) Listen/Src: No, No
Sensaura(tm) ZoomFX(tm): No

Description: Digital lyd (S/PDIF) (High Definition Audio-enhet)
Default Sound Playback: No
Default Voice Playback: No
Hardware ID: HDAUDIO\FUNC_01&VEN_10EC&DEV_0900&SUBSYS_1462D693&REV_1000
Manufacturer ID: 1
Product ID: 65535
Type: WDM
Driver Name: HdAudio.sys
Driver Version: 6.01.7601.17514 (Norwegian (Bokmål))
Driver Attributes: Final Retail
WHQL Logo'd: Yes
Date and Size: 11/20/2010 12:44:23, 350208 bytes
Other Files:
Driver Provider: Microsoft
HW Accel Level: Basic
Cap Flags: 0xF1F
Min/Max Sample Rate: 100, 200000
Static/Strm HW Mix Bufs: 1, 0
Static/Strm HW 3D Bufs: 0, 0
HW Memory: 0
Voice Management: No
EAX(tm) 2.0 Listen/Src: No, No
I3DL2(tm) Listen/Src: No, No
Sensaura(tm) ZoomFX(tm): No