diff --git a/tcpdf/TCPDF.php b/tcpdf/TCPDF.php
index 2fe8b72..ab4edc2 100644
--- a/tcpdf/TCPDF.php
+++ b/tcpdf/TCPDF.php
@@ -6256,11 +6256,11 @@ class TCPDF {
 			$charWidth = $charsWidth[$i];
 			if (($c != 160)
 					&& (($c == 173)
-						|| \preg_match($this->re_spaces, TCPDF_FONTS::unichr($c, $this->isunicode))
+						|| \preg_match($this->re_spaces, TCPDF_FONTS::$cache_unichr[$c] ?? (TCPDF_FONTS::$cache_unichr[$c] = TCPDF_FONTS::unichr($c, $this->isunicode)))
 						|| (($c == 45)
 							&& ($i > 0) && ($i < ($length - 1))
-							&& @\preg_match('/[\p{L}]/'.$this->re_space['m'], TCPDF_FONTS::unichr($chars[($i - 1)], $this->isunicode))
-							&& @\preg_match('/[\p{L}]/'.$this->re_space['m'], TCPDF_FONTS::unichr($chars[($i + 1)], $this->isunicode))
+							&& @\preg_match('/[\p{L}]/'.$this->re_space['m'], TCPDF_FONTS::$cache_unichr[$chars[($i - 1)]] ?? (TCPDF_FONTS::$cache_unichr[$chars[($i - 1)]] = TCPDF_FONTS::unichr($chars[($i - 1)], $this->isunicode)))
+							&& @\preg_match('/[\p{L}]/'.$this->re_space['m'], TCPDF_FONTS::$cache_unichr[$chars[($i + 1)]] ?? (TCPDF_FONTS::$cache_unichr[$chars[($i + 1)]] = TCPDF_FONTS::unichr($chars[($i + 1)], $this->isunicode)))
 						)
 					)
 				) {
@@ -6413,7 +6413,7 @@ class TCPDF {
 		$nb = \count($chars);
 		// replacement for SHY character (minus symbol)
 		$shy_replacement      = 45;
-		$shy_replacement_char = TCPDF_FONTS::unichr($shy_replacement, $this->isunicode);
+		$shy_replacement_char = TCPDF_FONTS::$cache_unichr[$shy_replacement] ?? (TCPDF_FONTS::$cache_unichr[$shy_replacement] = TCPDF_FONTS::unichr($shy_replacement, $this->isunicode));
 		// widht for SHY replacement
 		$shy_replacement_width = $this->GetCharWidth($shy_replacement);
 		// page width
diff --git a/tcpdf/include/TCPDF_FONTS.php b/tcpdf/include/TCPDF_FONTS.php
index 80e4da5..41b6f06 100644
--- a/tcpdf/include/TCPDF_FONTS.php
+++ b/tcpdf/include/TCPDF_FONTS.php
@@ -51,6 +51,7 @@ class TCPDF_FONTS {
 	 * @protected
 	 */
 	protected static $cache_uniord = [];
+	public static $cache_unichr = [];
 
 	/**
 	 * Convert and add the selected TrueType or Type1 font to the fonts folder (that must be writeable).
@@ -1724,7 +1725,13 @@ class TCPDF_FONTS {
 	 * @public static
 	 */
 	public static function UTF8ArrayToUniArray($ta, $isunicode=true) {
-		return \array_map(['TCPDF_FONTS', 'unichr'], $ta);
+		$temp = [];
+		foreach ($ta as $t) {
+			$temp[] = self::$cache_unichr[$t] ?? (self::$cache_unichr[$t] = self::unichr($t, $isunicode));
+		}
+
+		//return \array_map(['TCPDF_FONTS', 'unichr'], $ta);
+		return $temp;
 	}
 
 	/**
@@ -1745,7 +1752,7 @@ class TCPDF_FONTS {
 		}
 		$string = '';
 		for ($i = $start; $i < $end; ++$i) {
-			$string .= self::unichr($strarr[$i], $unicode);
+			$string .= self::$cache_unichr[$strarr[$i]] ?? (self::$cache_unichr[$strarr[$i]] = self::unichr($strarr[$i], $unicode));
 		}
 		return $string;
 	}