Change:
This increases the amount of work done when typing commands to be significantly more. Upstream:
Can't really verify this issue without debugging into the code, inside (formatted) you will see an function, the args are start/end. Add a breakpoint to that function and verify the args are a range for a single like (eg. 15, 15) after typing a single character into the terminal. Here is the failing case where the terminal is re-rendering lines 0-15: ! Use the canvas renderer to verify.
A better way to verify: to DOM renderer paint flashing: ! you type into the prompt only a single line will flash
Verified in latest (). Can this issue be closed?

Discussion:
"vscode-ripgrep": "^1.5.7", "vscode-sqlite3": "4.0.8", "vscode-textmate": "^4.3.0", <del> "xterm": "4.2.0", </del> <ins> "xterm": "4.2.0-vscode1", </ins> "xterm-addon-search": "0.3.0", "xterm-addon-web-links": "0.2.1", "yauzl": "^2.9.2",

"vscode-proxy-agent": "^0.5.1", "vscode-ripgrep": "^1.5.7", "vscode-textmate": "^4.3.0", <del> "xterm": "4.2.0", </del> <ins> "xterm": "4.2.0-vscode1", </ins> "xterm-addon-search": "0.3.0", "xterm-addon-web-links": "0.2.1", "yauzl": "^2.9.2",

"onigasm-umd": "^2.2.2", "semver-umd": "^5.5.3", "vscode-textmate": "^4.3.0", <del> "xterm": "4.2.0", </del> <ins> "xterm": "4.2.0-vscode1", </ins> "xterm-addon-search": "0.3.0", "xterm-addon-web-links": "0.2.1" }

resolved "https://registry.yarnpkg.com/xterm-addon-web-links/-/xterm-addon-web-links-0.2.1.tgz#6d1f2ce613e09870badf17615e7a1170a31542b2" integrity sha512-2KnHtiq0IG7hfwv3jw2/jQeH1RBk2d5CH4zvgwQe00rLofSJqSfgnJ7gwowxxpGHrpbPr6Lv4AmH/joaNw2+HQ== <del> xterm@4.2.0: version "4.2.0" resolved "https://registry.yarnpkg.com/xterm/-/xterm-4.2.0.tgz#b9980b2ae18c64ed31bcc95eace3bcecffebbbd9" integrity sha512-oNfLqt+LmghLPOt5UcskP5Km1fXpTBHsTZ99nxJKY2N0MNFXBKIVXUcNNhHCa74JGZFMGhLT58A/UN3HcPXSfg== </del> <ins> xterm@4.2.0-vscode1: version "4.2.0-vscode1" resolved "https://registry.yarnpkg.com/xterm/-/xterm-4.2.0-vscode1.tgz#dbd67e52536578ea6b772d69a97da1487acf29e3" integrity sha512-frw5Kprzkko8+G0vp4jOcwTeOpYFbSb2+QShpeQGJ7l3Hg3MTM7kt1G+nLxBPKnkFAmei/JcJTUGJdp/lldAfA== </ins>

resolved "https://registry.yarnpkg.com/xterm-addon-web-links/-/xterm-addon-web-links-0.2.1.tgz#6d1f2ce613e09870badf17615e7a1170a31542b2" integrity sha512-2KnHtiq0IG7hfwv3jw2/jQeH1RBk2d5CH4zvgwQe00rLofSJqSfgnJ7gwowxxpGHrpbPr6Lv4AmH/joaNw2+HQ== <del> xterm@4.2.0: version "4.2.0" resolved "https://registry.yarnpkg.com/xterm/-/xterm-4.2.0.tgz#b9980b2ae18c64ed31bcc95eace3bcecffebbbd9" integrity sha512-oNfLqt+LmghLPOt5UcskP5Km1fXpTBHsTZ99nxJKY2N0MNFXBKIVXUcNNhHCa74JGZFMGhLT58A/UN3HcPXSfg== </del> <ins> xterm@4.2.0-vscode1: version "4.2.0-vscode1" resolved "https://registry.yarnpkg.com/xterm/-/xterm-4.2.0-vscode1.tgz#dbd67e52536578ea6b772d69a97da1487acf29e3" integrity sha512-frw5Kprzkko8+G0vp4jOcwTeOpYFbSb2+QShpeQGJ7l3Hg3MTM7kt1G+nLxBPKnkFAmei/JcJTUGJdp/lldAfA== </ins> yauzl@^2.9.2: version "2.10.0"

resolved "https://registry.yarnpkg.com/xterm-addon-web-links/-/xterm-addon-web-links-0.2.1.tgz#6d1f2ce613e09870badf17615e7a1170a31542b2" integrity sha512-2KnHtiq0IG7hfwv3jw2/jQeH1RBk2d5CH4zvgwQe00rLofSJqSfgnJ7gwowxxpGHrpbPr6Lv4AmH/joaNw2+HQ== <del> xterm@4.2.0: version "4.2.0" resolved "https://registry.yarnpkg.com/xterm/-/xterm-4.2.0.tgz#b9980b2ae18c64ed31bcc95eace3bcecffebbbd9" integrity sha512-oNfLqt+LmghLPOt5UcskP5Km1fXpTBHsTZ99nxJKY2N0MNFXBKIVXUcNNhHCa74JGZFMGhLT58A/UN3HcPXSfg== </del> <ins> xterm@4.2.0-vscode1: version "4.2.0-vscode1" resolved "https://registry.yarnpkg.com/xterm/-/xterm-4.2.0-vscode1.tgz#dbd67e52536578ea6b772d69a97da1487acf29e3" integrity sha512-frw5Kprzkko8+G0vp4jOcwTeOpYFbSb2+QShpeQGJ7l3Hg3MTM7kt1G+nLxBPKnkFAmei/JcJTUGJdp/lldAfA== </ins> y18n@^3.2.1: version "3.2.1"