Lags of games are often caused by Internet connection, hardware specifications and server/client optimization. Also the problem may be caused by improper configuration of your video settings which in this case you either upgrade your video card or install new drivers. If you have an Intel, AMD or Nvidia graphics card, perform a fresh installation of your drivers by downloading the necessary ones. Also, having the latest Directx is a condition for smooth gaming.
Below are the Official minimum requirements for Need for Speed: World.
Required – Internet Connection
OS – Windows XP (SP3) / Windows Vista (SP2)/ Windows 7
Processor (XP) – Intel® Pentium® 4(HT) @2.4 GHz
Processor (Vista/Windows 7) – Intel® Core™2 Duo @ 1.8GHz
Memory (XP) – 1.0 GB RAM
Memory (Vista/Windows 7) – 2.0 GB RAM
Hard Drive – 2.0 GB
Video Card (XP) – NVIDIA® GeForce® 6800, ATI Radeon™ X1300, or Intel® GMA 950 (See "7. Troubleshooting" for support list)
Video Card (Vista/Windows 7) – NVIDIA® GeForce® 7600, ATI Radeon™ HD 2000 series, Intel® GMA 950 or better
Sound Card – DirectX 8.1 compatible
DirectX – Version 9.0c
Network Connection – 128 kbps Cable/DSL connection
Online Multiplayer – 512 kbps Cable/DSL connection; 2-8 Players
Input – Keyboard, Mouse, Supported Game Controllers (See section “8. Controller Information” for complete list)