Whenever any application like firefox is executed from unity launcher it takes 3 seconds and appears on screen (Unity 3D)

while in case of Unity 2D it run at the instant the icon gets clicked

The 3 second waiting really annoys me

System specs:
1 Gb RAM
Intel Pentium Dual Core Processor
lspci


00:00.0 Host bridge: Advanced Micro Devices [AMD] nee ATI Device 5a31 (rev 01)
00:01.0 PCI bridge: Advanced Micro Devices [AMD] nee ATI RS480 PCI Bridge
00:04.0 PCI bridge: Advanced Micro Devices [AMD] nee ATI RS480 PCI Bridge
00:05.0 PCI bridge: Advanced Micro Devices [AMD] nee ATI RS480 PCI Bridge
00:06.0 PCI bridge: Advanced Micro Devices [AMD] nee ATI RS480 PCI Bridge
00:07.0 PCI bridge: Advanced Micro Devices [AMD] nee ATI RS480 PCI Bridge
00:12.0 SATA controller: Advanced Micro Devices [AMD] nee ATI SB600 Non-Raid-5 SATA
00:13.0 USB controller: Advanced Micro Devices [AMD] nee ATI SB600 USB (OHCI0)
00:13.1 USB controller: Advanced Micro Devices [AMD] nee ATI SB600 USB (OHCI1)
00:13.2 USB controller: Advanced Micro Devices [AMD] nee ATI SB600 USB (OHCI2)
00:13.3 USB controller: Advanced Micro Devices [AMD] nee ATI SB600 USB (OHCI3)
00:13.4 USB controller: Advanced Micro Devices [AMD] nee ATI SB600 USB (OHCI4)
00:13.5 USB controller: Advanced Micro Devices [AMD] nee ATI SB600 USB Controller (EHCI)
00:14.0 SMBus: Advanced Micro Devices [AMD] nee ATI SBx00 SMBus Controller (rev 13)
00:14.1 IDE interface: Advanced Micro Devices [AMD] nee ATI SB600 IDE
00:14.2 Audio device: Advanced Micro Devices [AMD] nee ATI SBx00 Azalia (Intel HDA)
00:14.3 ISA bridge: Advanced Micro Devices [AMD] nee ATI SB600 PCI to LPC Bridge
00:14.4 PCI bridge: Advanced Micro Devices [AMD] nee ATI SBx00 PCI to PCI Bridge
01:05.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI RC410 [Radeon Xpress 200M]
02:00.0 Ethernet controller: Atheros Communications Inc. AR242x / AR542x Wireless Network Adapter (PCI-Express) (rev 01)
08:01.0 CardBus bridge: Ricoh Co Ltd RL5c476 II (rev b3)
08:01.1 FireWire (IEEE 1394): Ricoh Co Ltd R5C552 IEEE 1394 Controller (rev 08)
08:01.2 SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 17)
08:01.3 System peripheral: Ricoh Co Ltd R5C592 Memory Stick Bus Host Adapter (rev 08)
08:07.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)