While it isn't "fast" in the way modern languages like C++ or Rust are (for graphics or complex math), COBOL is exceptionally fast at high-volume data processing.

Why it’s "Fast"

Batch Processing: It is designed to move massive amounts of data (like millions of bank transactions) in and out of storage very efficiently.

Decimal Precision: Unlike most languages, COBOL handles "fixed-point" decimal math natively. This avoids the rounding errors common in other languages, making it faster and more accurate for financial calculations.

Hardware Optimization: It usually runs on mainframes where the hardware is specifically tuned to execute COBOL instructions at the chip level.

Why it’s "Slow"

Heavy Syntax: The code is wordy and "verbose," making it slower for humans to write and maintain.

Not Versatile: It is poor at tasks like image processing, 3D rendering, or real-time web applications.

Practicing mainframe technologies like DB2, COBOL, JCL, and CICS at home is possible using a combination of free IBM learning platforms, emulators, and specialized training resources. Direct access to a commercial mainframe system is typically not feasible for individuals, so these alternatives provide a practical environment. 

COBOL software is divided into compilers (to run the code) and IDEs (to write the code).

1. The Compilers (The Engine)

IBM Enterprise COBOL: The standard for IBM mainframes (z/OS).

Rocket Visual COBOL (Micro Focus): The industry leader for running COBOL on Windows, Linux, and Cloud.

GnuCOBOL: The top free, open-source compiler for personal learning and development.

2. The Editors (The Interface)

VS Code: The most popular modern choice (using the COBOL Language Support extension).

Eclipse / Visual Studio: Often bundled with professional tools like Micro Focus for a full-featured experience.

ISPF (The "Green Screen"): The traditional, text-based terminal interface used directly on mainframes.

The main difference is when the subprogram is linked to the main program.

Static Call

When: Linked at compile/link-edit time.

Structure: The subprogram is physically "baked into" the main program's executable file.

Pros: Faster execution (already in memory).

Cons: If the subprogram changes, you must re-link the entire application.

Dynamic Call

When: Loaded at runtime (execution time).

Structure: The subprogram remains a separate file and is only called when needed.

Pros: Easier maintenance; you only update the subprogram file, not the main program.

Cons: Slightly slower initial call due to the "search and load" overhead.

Absolutely Not.. Cobol is most commonly used in banking systems together with the IBM or other mainframe systems .The banking systems are quite sceptical to change their systems because finance systems are very well to show grudginess to change as its related to money .Also Cobol addons are nowadays available in many editors which is used to develop around cobol and integrate to many databases and systems but its still remain a large system used in banks to process transactions.More faster compilers are ebing developed around to make the process faster within the mainframe type systems