Look into JSDoc build performance

Expected Behavior

A JSDoc build with the UI5 Tooling should be as fast or faster to complete than when using the OpenUI5 grunt docs build

Current Behavior

❯ hyperfine --warmup 1 'grunt docs --force'
Benchmark SAP/ui5-builder#1: grunt docs --force
  Time (mean ± σ):     53.871 s ±  2.201 s    [User: 75.092 s, System: 5.580 s]
  Range (min … max):   51.555 s … 58.946 s    10 runs

❯ hyperfine --warmup 1 'npm run build-sdk' 
Benchmark SAP/ui5-builder#1: npm run build-sdk
  Time (mean ± σ):     111.163 s ±  2.921 s    [User: 158.006 s, System: 33.348 s]
  Range (min … max):   106.719 s … 115.586 s    10 runs

➡️ UI5 Tooling takes about 2x longer compared to grunt docs

Context

• UI5 Module Version (output of ui5 --version when using the CLI): 1.2.2
• Node.js Version: v11.8.0
• npm Version: 6.9.0
• OS/Platform: macOS 10.14.3

Affected components (if known)

• ui5-builder
• ui5-server
• ui5-cli
• ui5-fs
• ui5-project
• ui5-logger

Log Output / Stack Trace

{...}

Reproduce the reported comparison with grunt docs --force and npm run build-sdk, using the stated warmup and repeated benchmark runs. Compare the UI5 Tooling build against the OpenUI5 Grunt build and identify where the extra time occurs; done means documenting or addressing the cause so the UI5 Tooling JSDoc build is no slower than the reference.